Fig. 4. Sacculina triangularis; external skin and corium reflected: a, external skin covered internally by the corium; i, ovigerous lamellæ. Fig. 5. Ovigerous sac, showing the anterior and posterior folds which embrace the internal ovaries.

Fig. 6. Mass of ova from the ovigerous lamellæ.

Fig. 7. Greatly magnified view of one of the vesicles, drawn from a fresh specimen: a, the duct of the vesicle; c, the structure found in the

interior of the vesicle; b, the horny substance found at the com

mencement of the duct.

Fig. 8. The same organ as fig. 7, drawn from a specimen preserved in alcohol: a, the convoluted duct; b, the horny process.

Fig. 9. The structure found in the interior of the vesicle, removed. Fig. 10. Sacculina carcini, with no ovigerous lamellæ, nat. size: b, the peduncle; b', intestine of crab; c, ovario-branchial orifice.

Fig. 11. Sacculina triangularis, nat. size. (Same references as in fig. 10.)

Fig. 12. S. carcini distended with ova.

Fig. 13. Posterior view of fig. 12; d, horny attachment of peduncle; k, prolonged portion of the same.

Fig. 14. A group of S. triangularis.

Fig. 15. S. inflata (after Leuckart).

Fig. 16. Enlarged view of the vesicles of S. carcini.

II. Observations on British Zoophytes. 1. Hydractinia areolata, n. sp. 2. Atractylis arenosa, n. sp. (Plate XIV.) By JOSHUA ALDER, Esq. Communicated by T. STRETHILL WRIGHT, M.D.

1. Hydractinia areolata, n. sp. Plate XIV., figs. 1-4.

Polypary encrusting, consisting of a solid chitinous expansion, from which arise simple linear spines in irregular groups, leaving areolar spaces between them. Polyps naked, small, white, columnar, slightly enlarging above, and terminating in a conical mouth, below which is a single circle of from six to ten linear tentacles, appearing of different lengths from their varying contractility. Gonophores (reproductive organs) sessile on the chitinous base, large, globular, or slightly pear-shaped, containing each a single medusoid. Height of polyp about th inch.

Medusoid with a moderately deep subglobose umbrella, having four golden-yellow radiating canals, at the bulbous bases of which, on the margin of the umbrella, are four rather short tentacles; four shorter ones alternate with them; and intermediate between these are eight others, almost tubercular. The peduncle is rather long and co

lumnar, with four tufts of thread-cells surrounding the mouth.

A single specimen only of this interesting little Hydractinia was obtained, parasitical on a dead shell of Natica Alderi brought in by the fishing-boats at Cullercoats. I have since seen a dead and rather worn specimen, upon Natica Grænlandica, among the Zoophytes collected in Shetland by the Rev. A. M. Norman. The species differs from H. echinata in its much smaller size, the simple linear form of its spines, their irregular grouping, and more especially in its bearing medusoids; these latter spring from the encrusting base. No capsule could be detected; but this might possibly arise from its great transparency. The medusoids bear a great resemblance to those of Podocoryne carnea (Sars), the only difference being in their having eight intermediate tubercular tentacles. In this respect they also differ from the medusoid of a Hydroid polyp described by Professor Lovén, and referred by him to Hydractinia, but which appears rather to belong to the genus Podocoryne, as the base was not horny or spinous. As far as I am aware, therefore, this is the only instance in which medusoids have been ascertained to be produced by a true Hydractinia.

2. Atractylis arenosa, n. sp. Pl. XIV. figs. 5-7.

Polypary minute, consisting of a creeping fibre, from which arise short funnel-shaped tubes, rather irregular in form, but always expanding more or less at the top, from which the polyps issue, generally covered with minute grains of sand. Polyps entirely retractile, with long, slender, strongly muricated tentacles, varying in number, according to age, from six to twelve.

The genus Atractylis has been established by Dr Strethill Wright for a group of Hydroid Zoophytes resembling Eudendrium in many of their characters, but differing in the conical form of the mouth of the polyp, and its retractility (partial or complete) within the tubular polypary. They are generally of small size, and seldom branched. Their reproduction is usually by medusoids; but Dr Wright, who

has lately met with the present species in the Firth of Forth, has ascertained that it produces planuloid young direct from the summit of the ovarian sac. This affords another proof of the difficulty of establishing a genus from the mode of development.

I have met with this species occasionally, for some years past, on stones and the roots of Laminaria at Cullercoats and Tynemouth. From its minute size, it requires to be carefully looked for.

Explanation of Plate XIV.

Fig. 1. Polypary of Hydractinia areolata on Natica Alderi, natural size.
Fig. 2. Hydractinia areolata, highly magnified.

Fig. 3. A portion of the polypary of the same, highly magnified.

Fig. 4. Medusoid of the same, highly magnified.

Fig. 5. Atractylis arenosa, natural size.

Fig. 6. The same, highly magnified.

Fig. 7. A tentacle of the same, much enlarged.

III. On Reproduction in Æquoria vitrina. By T. STRETHILL
WRIGHT, M.D. Plate XV.

In vol. i. of Agassiz's "Natural History of the United States," the following passage occurs:-" As to the Equoriadæ, I have no doubt that they are genuine hydroids, though I have not been able to trace with certainty the origin of the Equoria of our coast to any true hydroid. But the structure of Equoria in its adult Medusa state is so strictly homologous to that of all the naked-eyed Medusa, that even if it were ascertained that it undergoes a direct metamorphosis from the egg to the perfect Medusa, I would not hesitate to consider it as a member of the order of Hydroids, since it has simple radiating aquiferous tubes, a circular canal, and marginal tentacles closely connected with it, and provided with minute pigment spots at the base." Agassiz was doubtless correct, and he might also have predicted that it belonged to the genus Campanularia or Laomedea, as it corresponded with those genera in the presence of otoliths. In the beginning of this month (November) Mr Fulton sent me two living specimens of Equoria vitrina, one about three inches in diameter, the other about six

inches and a half. The number of lips of the latter was about forty, the radiating canals, each having a long ovisac, about eighty, and the marginal tentacles, by estimation, four hundred. On examining the ovaries, I found that the eggs were hatched, and the young, in the form of almost invisible planulæ, were issuing from the ovisacs. These were gently extracted with a glass syringe, an instrument so useful to those who practise the obstetric art amongst the hydroidæ, and were placed about three weeks ago in glass tanks of clean sea-water prepared for their reception. Many thousands of larvæ were placed in the tanks, and of those, about a score have been developed into Campanularian polyps; about a hundred are still progressing to that end, and the rest have disappeared. It was with no little impatience and anxiety that I saw the Planula during a fortnight fix itself to the glass, spread itself out into a short thread, secrete its scleroderm, put forth its polyp-bud—this last slowly swelling day by day, until at last it opened, and a polyp appeared, furnished with twelve alternating tentacles, joined together for about one-third of their length by a web, the polyp enclosed in a cell terminating in many acuminate segments. It is now about six years ago that I was watching, in like manner, the slow evolution of a bud from a Campanularian Zoophyte, the Laomedea acuminata of Alder-the Campanulina of Van Beneden- the bud opened, and a bright green medusoid issued forth, having four lips and two tentacles. The polyp form of Equoria vitrina is, as far as I can determine, identical with that of L. acuminata in shape; but is so excessively small-quite invisible to the naked eye-that we must wait for further development before we can determine their identity. Geganbaur has proved that the Medusoid of Velella acquires a further number of canals and tentacles; and I have elsewhere recorded the successive changes which occur in the Medusoids of several species of Atractylis. It is also certain that such increase in the number of elements does occur in Equoria vitrina, for the smaller specimens have always a less number than the larger. Meantime, the question as to the larval state of Equoria vitrina is settled. This, the

largest of all the naked-eyed Medusas, is the reproductive phase of one of the smallest of all the Hydroidæ.

Explanation of Plate XV. Equoria vitrina.

1. Planula directly after leaving the ovary.

2. Same a week old.

3. Same after having fixed itself to the glass and developed its scleroderm, -now become a polypary.

4. Polypary putting forth bud.

5. Same with young polyp.

6. Empty polyp cell.

IV. The following Objects of Natural History were exhibited by EDWARD CHARLESWORTH, Esq., York.

A stuffed specimen of the Frilled Lizard Chlamydosaurus Kingii, from Port-Nelson, New Zealand, believed to be the best example yet seen of this most extraordinary reptile. It was purchased at the sale of the late Dr Mantell's Museum.

A small but extraordinary coral from the Chinese Seas, believed to be undescribed.

A series of small fossil tertiary shells from Barton, in Hampshire, illustrated by magnified figures.

A collection of small recent British Marine shells, illustrating a new mode of mounting and exhibiting very small specimens, intended to insure safety with effective display. The shells were fixed on cards with gum tragacanth, which can be freely brushed across the surface, and thus save much time in mounting, as it does not shine when dry, like gum arabic. The cards are then put in small boxes with glass lids.

A specimen of Mactra Helvacea, and other shells from the Channel Islands; several rare fossils of various kinds were also exhibited.

Monday, 16th December 1861.-ALEXANDER BRYSON, Esq., President, in the Chair.

:-

The Office-Bearers for the Session 1861-62 were elected as follows: Presidents.-Alexander Bryson, Esq.; James M'Bain, M.D., R.N.; John Coldstream, M.D.

Council.-William Rhind, Esq.; David Page, Esq.; William Turner, Esq., M.B.; Thomas Strethill Wright, M.D.; George Berry, Esq.; A. M'Kenzie Edwards, Esq.

Secretary.-John Alexander Smith, M.D.
Treasurer. George Logan, Esq.

Assistant Secretary.-James Boyd Davies, Esq.
Honorary Librarian.—Robert F. Logan, Esq.

Library Committee.-W. H. Lowe, M.D.; John Anderson, M.D.; John S. Livingston, Esq.

The following gentlemen were elected ordinary members of the Society :

Murray Thomson, M.D., F.C.S., Lecturer on Chemistry; A. G. H. Cameron of Lakefield, Esq., Inverness-shire; Thomas Chapman, Esq.,