by about 1 in its greatest breadth, and exhibits a transverse, or rather radiating, series of eight depressions, gradually increasing in depth, and showing lines of punctures, corresponding, he supposed, to the rows of the projecting teeth ; and the fossil was all the more strikingly displayed from the colour of the sandstone being completely discharged around the cast, which appears as a patch of white, in the dull red of the surrounding stone. He sent the fossil for examination to Mr Hugh Miller a few months before his lamented death, and received, in reply, the following interesting note :- .

“SURUBMOUNT, 30th June 1856. “My dear Sir,-Your fossil is the Old Red Ctenodus of Agassiz (his Coal Measure Ctenodus belongs to a different genus); but though he gives it (his Old Red Ctenodus) a generic standing of its own, it is in reality a portion of the previously described Dipterian genus. The Dipterus had two triangularly arranged groups of teeth on its palate, and your specimen is a remarkably distinct impression made by one of these I could show you groups of teeth, were you to do me the pleasure of looking in upon me here, that would fit into your impression well nigh as exactly as a seal would into the wax which it had stamped. Your specimen is the second of Dipterus which I have now seen from the Upper Old Red Sandstone. The first,-a gill cover,-is in the collection of Mr Patrick Duff of Elgin. I have been prostrated by another attack of my old enemy, inflammation of the lungs, and, after being confined to my bed for a fortnight, am but slowly recovering. Portobello has many visitors at present; but I have seen little of scientific men, and have had little of scientific conversation for the last three quarters of a twelvemonth ; and should you chance to come this way, it would gratify me much to have half an hour's talk with you among my fossils. Some of my Old Red ones would, I am sure, cast not a little light on the detached organisms of your south-country beds.—1 am, my dear Sir, yours very truly,

“Hugh Miller. “Dr John A. Smith.”

Wednesday, 220 December 1858.-William Ruind, Esq., President,

in the Chair,

J. W. Laidlay, Esq. of Seacliff, and John M. Mitchell, Esq., Mayville, Trinity, were elected members of the Society.

The Office Bearers for the session were elected as follows:

Presidents.-Andrew Murray, Esq., W.S.; William Rhind, Esq. ; Thomas Strethill Wright, M.D.

Council.-W. H. Lowe, M.D.; Alexander Rose, Esq.; George Logan, Esq., W.S.; John Hutton Balfour, M.D., Professor of Botany, University ; James M'Bain, M.D., R.N.; John Coldstream, M.D.

Secretary.-John Alexander Smith, M.D.
Assistant Secretary.-James Boyd Davies, Esq.
Treasurer.-William Oliphant, Esq.
Honorary Librarian.--Robert F. Logan, Esq.

Library Committee.—John L. Stewart, Esq. ; Alexander Bryson, Esq. ; Patrick Dalmahoy, Esq., W.S.

The following Donations to the Library were laid on the table, and thanks voted to the donors :

1. Annales des Sciences Physiques et Naturelles d'Agriculture et d'Industrie, Publiées par la Société Royal d'Agriculture, &c., de Lyon, Tomes VI., VII., VIII., IX., X., and XI.-From the Royal Society of Agriculture and Industry of Lyons. 2. Geological Survey of Canada Report of Progress for the years 1853–56, printed by order of the Legis

lative Assembly, Toronto; with quarto Atlas of various lakes and rivers. ---From Sir W. E. Logan.

The following communications were then read :

I. Mr Rhind exhibited a specimen of black shale, displaying a branch of Lepidodendron several inches in length, with the Lepidostrobus attached to its extremity, which was found by Mr R. H. Traquair, in the beginning of August last, in a stratum of very fissile black shale exposed in the bed of the Water of Leith, a little below the church at Colinton, This shale abounds in the stems of Lepidodendra, in detached Lepidostrobi and Lepidophylli ; and in what seems to be impressions of very delicate bivalve shells ; also in Cyprides, and detached scales of the Palæoniscus. Notwithstanding the abundance of the two first-mentioned fossils (Lepidodendron and Lepidostrobus), this specimen is the only one Mr Traquair had ever found exhibiting them in distinct apposition.

II. On the Cnidæ or Thread-cells of the Eolidæ. By T. STRETHILL

WRIGHT, M.D. Dr Wright, after describing the anatomy of the respiratory, digestive, and hepatic organs in the Eolidæ, stated that, in his Memoir on Hydractinia echinata, read before the Society, November 26, 1856, he had observed, “ Hydractinia is infested by a small species of Eolis (Eolis nana), which peels off the polypary with its rasp-like tongue, and devours it,possessed, I suppose, of some potent magic, which renders all the formidable armament of its prey of no avail. Now, each of the dorsal papillæ

of the Eolidæ contains at its extremity a small ovate vesicle, communicating, through the biliary sac, with the digestive system, and opening externally by a minute aperture at the end of the papillæ. This vesicle is found crowded with compact masses of thread-cells ; which inasses, in Eolis nana, consist of aggregations of small and large thread-cells, identical in size and shape with those of Hydractinia,—on which this Eolis preys,—not contained in capsules, but cemented together by mucus. When we consider that each of the vesicles is in indirect communication with the stomach, I think we may, without presumption, suggest that the masses of thread-cells found in Eolis nana are quasi fæcal collections of the thread-cells of Hydractinia, which, protected by their strong coats, have escaped the digestive process. In corroboration of this view, I may mention that the thread-cells of Eolis papillosa, as figured in the work of Alder and Hancock, have a perfect resemblance to those found in the Actinias, which last animals furnish an Abyssinian repast to these carnivorous mollusca.” Dr Wright afterwards found that, as to the above idea, he had been anticipated by his friend Mr Gosse, who, in his “Tenby,” after noticing the existence of the thread-cells in the papillæ, remarks :-“The inquiry I suggest would be, How far the presence of thread-cells might be connected with the diet of the mollusc? And whether, seeing the forms of the missile threads vary in different genera of zoophytes, the forms of the corresponding organs in the papillæ of the Eolides would vary if the latter were fed exclusively first on one and then on another genus of the former.” He afterwards found that Mr Huxley had also doubted, previously to Mr Gosse and himself, whether the thread-cells of the Eolidæ were not adventitious. Here were three independent observers to whom the idea has suggested itself; Mr Huxley had first hinted it; Mr Gosse suggested it, and how it might be found to be true; Dr Strethill Wright also had suggested it, and given two instances in corroboration of his opinion, and to-night he proceeded to detail observations which would, he hoped, entitle it to be enrolled as a proved fact in the records of science. 18t, A specimen of Eolis nana was brought home from Morison's Haven, on a shell covered with Hydractinia, taken from a rock-pool, in which was a profuse growth of Campanularia Johnstonic. The papillæ of this Eolis contained the two kinds of thread-cells which are found on Hydractinia, together with the large thread-cells which occur within the reproductive capsules of C. Johnstonii. 2d, An Eolis coronata was taken at Queensferry, on a massive specimen of Coryne decipiens, which was very abundant there. The thread-cells of C. decipiens were very distinctive, being very large, oval, and containing a four-barbed dart. The thread-cells of the Eolis and Coryne were carefully compared together, and were found to be identical. 3d, Dr M.Bain and Dr Wright found an Eolis Drummondii on a fine specimen of Tubularia indivisa. They first carefully examined

the thread-cells of the Tubularia, and found four kinds, two (large and
small) of a nearly globular shape, each containing a four-barbed dart,
and two (large and small) of an almond shape, the larger one containing
a thread, furnished with a lengthened brush of recurved barbs. They
then examined the papillæ of the Eolis, and found the ovate sacs filled
with an indiscriminate mixture of all the four kinds of thread-cells found
on Tubularia indivisa. 4th, Dr M.Bain and Dr Wright found a speci-
men of Eolis Landsburgië on Eudendrium rameum. Eudendrium
rameum was furnished, as to the bodies of its polyps, with very large
bean-shaped thread-cells, in which an unbarbed style could be detected,
while the tentacles of the polyps are covered with exceedingly minute
cells. They compared the thread-cells of the Eudendrium with those
found in the sac of Eolis, and found both kinds identical. Lastly, Dr
Wright had kept the specimen of Eolis Drummondii above-mentioned
fasting for a long time, and then introduced it to a large specimen of
Coryne decipiens fresh from the sea. The next morning every polyp
of the zoophyte bad vanished, and the ovate sacs of the Eolis were
packed with the distinctive thread-cells of the Coryne, mixed with a few
thread-cells of T. indivisa, the remains of its former feast. He also
found the thread-cells of C. decipiens in the alimentary canal. It was at
one time supposed that thread-cells, or Cnidæ, as Mr Gosse had named
them, were only to be found in the hydroid and helianthoid polyps and
the Medusæ; Professor Allman afterwards discovered them in a species
of Loxodes, a protozoan animalcule; and Dr Wright had the good fortune
to find them on the tentacles of an annelid, Spio seticornis, and also on
the tentacles of Cydippe, one of the Ctenophora. Since then he had
observed them on the very minute tentacles of Alcinöe, another of the
Ctenophora. In all these classes of animals thread-cells were developed
within the ectoderm or skin of the animal, and in many, such as in
7. indivisa, each within a distinct and very apparent sac, and not in
connection with the digestive system. The type of structure, moreover,
of the thread-cell in the Protozoon, the Polype-medusa, the Annelid, and
the Ctenophore, was essentially different for each class; and this fact
alone would lead one to doubt as to the origin of the thread-cells of Eolis,
which so exactly resembled those of the polype-medusæ in their structure.
Nevertheless, it was certainly a very strange fact, for a fact the author
firmly believed it to be, that one animal should be furnished with appa-
ratus for storing up and voluntarily ejecting organic bodies derived from
the tissues of another animal devoured by it, and that these should still
retain their destructive functions unimpaired; and he stated that his
friend Mr Alder, one of the highest authorities on the Nudibranchs,
still hesitated to assent to the doctrine sought to be proved by the pre-
sent communication, on the ground of its extreme improbability.

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III. Notice of a Skull of the Troglodytes Niger, Desm., the Chimpanzee,

found in a Devil-house,Old Calabar, Africa. By John Alexr. SMITH, M.D.

The skull on the table was one of those interesting objects of natural history, for the exhibition of which the Society is indebted to the zeal of our Treasurer, Mr William Oliphant, and, through him, to the missionaries of the United Presbyterian Church at Old Calabar. It was sent home by Mr Archibald Hewan, the Mission surgeon, and was entitled by him the skull of an ape, taken from an old "devil-house” at the Guinea Company's villages, about a hundred miles from the mouth of the Old Calabar River. It is the skull of an adult Chimpanzee, indicated by its general appearance, the calvarium smooth and rounded, the partially obliterated sutures, and the full complement of teeth, well ground down on their summits. These teeth are similar in number to those of man. The skull measures 19 inches in circumference, in the line of the alveolar processes of the incisor teeth in front, and the occipital protuberance behind ; and rather more than 7 inches in length between the same points in a straight line. The skull of an adult male is described as measuring 8.inches in length; this is probably therefore the skull of an old female,—the muscular ridges being but slightly marked; the space between the incisor teeth and the canines is very slightly developed, measuring little more than 1-10th of an inch. The characteristic high superciliary ridge of the Chimpanzee is strongly marked; showing at a glance the very vague character of any deductions as to the amount of brain, to be drawn from the extent of what is called the facial angle in a cranium such as this. This formidable animal stands some 3 feet 10 inches high, the male reaching the height of 4 feet from the top of the head to the sole of the heel in a straight line. You are aware these creatures have been frequently described as reaching a much higher stature (it was believed with increasing age), but it now appears from the recent researches of naturalists, both in America and in this country, that there are at least two distinct species of Chimpanzee, inhabiting in one instance the same district of country, one of which is much larger than the other. The cranium now exhibited be


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