method of investigation of the Spongiada, undertaken by Dr Bowerbank; and from his well-known microscopic ability, persevering industry, and accuracy as an observer, no one is better qualified for the task, nor more likely to do full justice to it. In the paper referred to, the early stage and development of spicula is described. "They appear to consist of a double membrane, between which the first layer of silex is secreted, and in this condition they present an internal cavity approaching very nearly to the size of their external diameter. In this state they readily bend abruptly in any direction without breaking. An interesting fact, in regard to the animal nature of the sponge, is, that many forms of the spicula have their types in the more highly organised class of animals, and especially among the Zoophyta, the Tunicata, and the Nudibranchiate mollusca. The spicula are always of an organic type, and never crystalline or angular. Each species of sponge has not one form of spiculum only, equally dispersed throughout its whole substance, but, on the contrary, separate parts have each its appropriate form, and three, four, or even more forms often occur in the same individual; and in Tethea cranium there are no less than seven distinct shapes. The spicula appropriate to particular parts of the sponge are uniform in their general characters throughout the whole of the Spongiada, and a great portion of them are so well characterised by their form as to enable the student, when once well acquainted with their peculiarities, to assign each readily to its proper place in the sponge." These organs are treated of in the following order : 1. Spicula of the skeleton. 2. Connecting spicula. 3. Defensive spicula. 4. Spicula of the membranes. The monograph is accompanied with four beautiful plates, containing upwards of two hundred figures of the different forms of spicula, with a distinct appellation for each form. The scientific world is therefore indebted to Dr Bowerbank for a new arrangement of the Spongiado, with a precise terminology and nomenclature, founded on the anatomical structure and physiology of the species. I have taken this opportunity to give a brief notice of these recent investigations and discoveries, as they are unquestionably the most valuable additions to our knowledge of the Spongiada, since the original contributions of Dr Robert Grant, published in the “Edinburgh Philosophical Journal" for 1826. III. Report of the Committee on Marine Zoology; with a Notice of the Sprat-Fishing in the Firth of Forth. By GEORGE LOGAN, Esq., Convener. (With exhibition of specimens). Mr George Logan, W.S., the Convener, read the report of the proceedings of the Committee on Marine Zoology for the past year. The Committee, among numerous other captures, obtained a fine specimen of Corystes cassivelaunus, the masked crab, dredged up in Aberlady Bay. Living specimens of Kellia suborbicularis, found plentifully in dead valves of Tapes virginea, near Inchkeith, in September last, lived for rather more than six weeks. Although great numbers of the hermit crab, Pagurus, were examined, dredged in about six fathoms water, in expectation of finding the parasite Peltogaster paguri frequently attached to it, not a single specimen was discovered. Sacculina carcini was found at Trinity attached to the abdomen of the common edible crab, sometimes two or three on one animal. To show how very little particular the hermit or soldier crabs are in the choice of their residence, one was dredged up near Inchkeith ensconced in the large head of an ancient-looking tobacco pipe, covered with barnacles. One specimen of Psammobia Ferroensis was found near Inchkeith; and occasionally on old valves were observed the curious pear shapes, stalked ovarian niduses, of Pontobdella muricata, frequently passed over as the undeveloped state of Himanthalea lorea; some specimens were also procured of Nemertes Borlassii, of a beautiful full dark purple colour, and of enormous length. On the 28th of September four or five specimens of a small flat fish came up in the dredge, which appears to be the Monochirus linguatulus (Cuvier), first observed in this country by Parnell on the Devonshire coast, and noticed by him in 1837 in the Transactions of the Royal Society of Edinburgh, and in the "Magazine of Zoology and Botany," under the name of Monochirus minutus. He does not include it in his "Fishes of the Firth of Forth," and the Committee are not aware of its having before been obtained there; but from the occurrence of so many specimens in one day, it would seem to be not very rare. Some of the specimens were brought home alive, and one of them lived for nearly three months, until killed by the recent severe cold. It was very sluggish, remaining always at the bottom of the aquarium, and seldom moving unless disturbed. When fishing with the seine net along the shore eastward of Leith, a number of species were taken, which will give some idea of the fishes which occur on this limited portion of the coast. The most abundant fish, of course, by far, is the mud flounder, Platessa flesus, along with which were always a considerable number of plaice, Platessa vulgaris, and a few salt water flounders, P. limanda, the proportion of the latter being very small to the other two. One or two specimens. of the common sole occurred during the season, and a single specimen of the brill, Rhombus vulgaris. Numbers of small thornbacks, Raia clavata, occurred along with these on the sandy portions of the shore, mingled with shoals of young Trigla. The sting fish, Trachinus vipera, the armed bullhead, Aspidophorus cataphractus, and the one-spotted goby, Gobius unipunctatus, were in abundance in spots where much ulva and enteromorpha grew. Two or three specimens of the common pipe fish, Syngnathus acus, occurred along with these, and a considerable number of the green cod, Merlangus virens. A few specimens of the viviparous blenny and five-bearded rockling also occurred, and a single specimen of the sordid dragonet, Callionymus dracunculus, and one of the short spined cottus, Cottus scorpius. The spotted gunnel fish, Muraenoides guttata, was not scarce in pools among the Black Rocks, and proves a most admirable fish for the aquarium, living long, and becoming quite tame when fed with small earth worms. Two small salmon trout (Salmo trutta) were caught during the season, each about two pounds in weight, one close to the Black Rocks, and the other near Portobello. The Committee made reference to the herring and sprat or garvie fishery of the Firth of Forth, which has recently excited so much interest, and upon which so much contradictory has been said and written. Certain members of the Committee devoted much time and attention to the subject, examining separately the product of the fishery in the boats and in the fish-carts since the 4th of the current month of January, when the Fishery Commissioners withdrew the prohibition against sprat-fishing; and the result of close investigation of large masses of fry at various times has been, that the proportion of herring, Clupea harengus, less than 6 inches long, taken among the sprats, Clupea sprattus, is very small; one of the examiners found on an average only one herring fry among a hundred sprats over a very extensive field of investigation; others found the proportion of herrings rather larger; but they all concurred in thinking that the comparatively small quantity of herring fry caught with the sprats could not in any sensible degree affect the former; and when it is considered that the roe of a single herring contains such an enormous quantity of ova (32,000), and that the fish spawns upon our shores in countless millions annually, the sensitiveness which has been shown as to the taking of even a few tens of thousands of young herrings among the sprats seems to be without foundation. A limited close-time, or protection in a limited area, would probably do infinitely more towards the protection of the fishery than any needless and unpopular prohibition of sprat or other fishing. Specimens of the smallest size of herring and the largest size of sprat ordinarily occurring amongst the masses caught were exhibited; and, although the distinguishing marks were very apparent, even to the ordinary spectator accustomed to the appearance of the fish, there seemed to the Committee to be no mode of accounting for the outcry, so far as honest, which has been made about the destruction of herring fry, but upon the supposition that the two descriptions of Clupea, the herring and the sprat, have not been accurately recognised, and that well-grown herrings have been denominated fry. The abiding scientific distinctions are so well known that they need not be repeated. Dr Parnell has very concisely and most accurately stated them, as noticed in the last Report of the Committee; but it may be useful to mention the prominent and easily noticed markings which separate the two species, so that any one upon looking over the surface of a mass of fish so abundantly brought to market, may distinguish without difficulty the one from the other. The head of the herring, from the point of the lower jaw to the farthest part of the gill plates, is about a fourth part longer than the head of the sprat; the eye is one-third larger; the lower jaw projects more beyond the upper jaw; the tail of the herring is dark; that of the sprat light-coloured, much broader, shorter, and less forked than that of the herring; and the body of the fish at the insertion of the tail is also much broader; the abdominal line is strongly serrated and sharp all along; the same line in the herring is rounder and quite soft (excepting in small specimens, but there is never any serration under the pectoral fins); the sprat is more plump and compact, and resembles in shape a miniature salmon, and the scales are larger, and their insertion much farther apart. than in the herring. Upon the vexed subject of herring spawn it may be stated, that during several years while the herring have been upon the coast in abundance, the Committee, from the beginning of August to the middle of October, have dredged and trawled in Aberlady Bay and off North Berwick down to Tyningham Sands, without bringing up a trace of herring spawn; and they are quite satisfied that none is deposited upon proper trawling or dredging ground. Among the millions of fry which have come under the observation of the Committee during the present month not a single specimen of whitebait, Clupea alba, has been detected, and, what is somewhat remarkable, although whitebait was found in abundance at Seafield in the autumn of 1859, as the Committee then reported, without any admixture of sprats; during last season, at the same period, only sprats were found without any whitebait. A vote of thanks to the Committee on Marine Zoology, and to Mr George Logan, Convener, was moved by the President, and was unanimously agreed to. VOL. 11. 21 |