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away the surrounding lias; which may also account for its less symmetrical form, unpolished surface, and the absence of the marginal rim. The processes in both cases unquestionably gave attachment to powerful moving muscles; the central serving to direct the spine forwards, the lateral to either side, and all to fix and steady it. From the more expanded direction of the lateral processes, also, the spine of Hybodus Delabechei must have been capable of a greater extent of motion from side to side than that of the wealden species; and the nature of the instrument itself shows that it must have been a powerful weapon of offence. The specimen here described farther proves that, like the horn of the rhinoceros, it was connected with the bones of the skull, only by muscles; but, unlike, that instrument, it must have possessed great powers of motion. M. Agassiz, is said to have a manuscript note of the only species of Hybodus which has been hitherto discovered in the wealden formation. Whether the fragment here described may eventually prove to belong to that or a different species, time must determine ; but it is interesting to know that the character of the frontal spine, first discovered by Mr. Charlesworth, is not confined to the Hybodus Delabechei, but common to the whole genus; or at least to the males, as in the allied genus Chimera.

Art. V.Letter addressed to the Editor by HENRY Woods, Esq.,

F.L.S., &c., respecting the supposed Frontal Spine of Hybodus in the Bath Museum.

30, Henrietta St., Bath,

May 12th, 1839. ME DEAR SIR,

A letter addressed by you to Mr. H. Jelly (who, I am sorry to state, has been for some time absent from Bath in consequence of ill health) having been handed over to me, I proceed to give you as good an answer as is in my power.

Before the receipt of your letter to Mr. Jelly, I had searched over the Museum of our Institution for the specimen mentioned by Mr. Lonsdale, and was fortunate enough to find it, or at least that which I consider to be it; and here you have the best drawing I can make, which I hope is precise enough for your purpose. It is of the natural size, and, from some peculiarities, may indicate another species of Hybodus : fig. 38, a, is a lateral, and b a dorsal view of it. The specimen measures 1} inch in length, and 6 of an inch in breadth

1

near the base, which is much mutilated. The apex is unfortunately broken off, but enough remains to show that, when perfect, it described a reversed curve at the end, as in fig. 38,

38

с

c.

Spine of Hybodus. Another peculiarity is the barb, or recurved hook, near the point-a, which, in your specimen, may have been broken off. * Unfortunately, no part of the tri-lobed bony base is attached to this specimen, which has been broken into four pieces. Two of the three fractures occurred before it was found; and I think the curved form of the dorsal aspect is in a great measure owing to the edges of the fractured parts not being in exact juxta-position, the interstices being filled with clay.

I'wo peculiarities, in addition to those above enumerated, I consider to be worthy of notice. One is a raised and oblique lateral line, as seen in fig. 38, a; and the other, a number of nearly parallel striæ or ruga on the dorsum, which so nearly resemble those upon the palatal or dental bones of the Acrodus , (vulgatè Leeches of the quarrymen), that I cannot help thinking this is rather a palatal than a nasal appendage, notwithstanding its extraordinary shape. Whether it may be identical with your specimen, or belong to some kindred species, or be altogether foreign to it, you must yourself judge; at any rate, it appears to me an object of interest, and you are perfectly welcome to make what use you please of this communication, which I can only regret is not more satisfactory both in figure and description."

Yours very sincerely,

H. Woods. Editor of the Magazine of Natural History.

1 The specimen was found in the lias at Weston, a village two miles west of Bath; and was presented, about twelve or thirteen years ago, to the Museum of the Institution, by Jacob Wilkinson, Esq.

ART.VI.—Catalogue of the Malacostracous Crustacea of South De

By EDWARD MOORE, M.D., F.LS., Secretary to the Plymouth Institution. It would appear almost superfluous, after the labours of Montagu and Leach, to attempt to take up the subject of the Malacostraca of Devonshire, as it constituted almost the chief field of their discoveries ; nevertheless, in pursuance of my original object, to attempt to collect as many illustrations of the Fauna of this county as circumstances will allow, I shall make no apology for endeavouring, “haud passibus æquis,” to follow in their steps: with this view I have sought from all sources within my reach, to ascertain what species have already been noticed, so as, by arranging them in the following catalogue, to lay the foundation of a more perfect acquaintance with some of the natural productions of our coast. The existence of a very excellent collection in the Museum of the Plymouth Institution, for which we are principally indebted to Mr. Charles Prideaux, of Hatch Arundel, near Kingsbridge, together with the advantages which I obtain by a correspondence with him and with Mr. J. Couch, of Polperro, will, I hope, render my catalogue not unacceptable to naturalists generally; and as I observe that Mr. Bell is shortly about to publish a work on British Malacostraca, I am unwilling that in the county of Montagu and Leach the subject should appear to be altogether neglected, possessing as it does such remarkable advantages for the pursuit. Yet, after all, it must be confessed that my paper will aim at no higher pretensions than that of a Catalogue, as in most instances it is almost impossible to obtain information beyond the mere fact of the occurrence of many species, which, living in deep water, all chance of obtaining any knowledge of their habits is precluded. In such cases, although I have been able to verify most of the observations of my predecessors, I

preferred letting the fact of existence stand in their names, merely referring to the works where their communications are to be found. There are, however, some species which I have been unable to identify as Devon specimens, from an inability to obtain access to works not procurable in this remote part of the scientific world; a deficiency, however, the less to be regretted, as it will most probably be supplied in Mr. Bell's expected work on British Crabs, a publi

We received the present catalogue from Dr. Moore in the month of September, 1838; but owing to the number of communications in hand, we have been unable to give it earlier insertion.--Ed.

this quarter.

cation which will be highly acceptable to all naturalists in

In the following paper I have followed Cuvier's 'Règne Animal,' in which the Crustacea were arranged by Latreille.

The class Crustacea in the 'Règne Animal' has two sections, viz., MALACOSTRACA and ENTOMOSTRACA.

The Malacostraca are composed of five Orders, viz., Decapoda, Stomapoda, Amphipoda, Lemodipoda, and Isopoda.

MALACOSTRACA with pediculated moveable eyes. Order I.-Crustacea Decapoda. These have the head close

ly united to the thorax, both of which are inclosed in one entire shell or carapace, divided by lines into different regions, which indicate the places occupied by the principal interior organs; they have a vascular and nervous system; the lateral borders of the carapace fold down to protect the branchie, leaving an opening anteriorly for the passage of the water; the six jaw-feet are all of different forms, applied to the mouth, divided into two branches, the exterior of which is like a small antenna; the two anterior, and sometimes the four following feet are talon-shaped, the last articulation but one is dilated, compressed, and in the form of a hand. Family 1. Decapoda brachyura, or short-tailed Decapods.

Genus CANCER. Section 1. Pinnipedes or swimmers have the last feet with a

flattened or fin-shaped articulation. POLYBIUS, sub-genus. P. Henslowii. A fine specimen was obtained from the pilchard-nets at

Bantham, in deep water, by Mr. C. Prideaux, and is now in the col

lection of the Plymouth Institution. PORTUNUS, sub-genus. P. puber, Harbour or Mary Crab. Common on our coast; three speci

mens are in the Museum of the Plymouth Institution. P. mænas, (Carcinus, Leach), Common shore Crab. Abundant. P. corrugatus. Dr. Leach says ('Linn. Trans.' vol. xi.) “habitat in Bri.

tanniả rarissimè;" and afterwards states that the young was obtained in Plymouth Sound by Mr. C. Prideaux, who informs me that he procured it by the trawl net. My friend Mr. Couch, of Polperro, also states that he has obtained one specimen in his neighbourhood, so that it may be considered as belonging to our coast, although but rarely

found from its habit of frequenting the deep sea. P. marmoreus. Frequently obtained at Torcross by Montagu; Edinb.

Encycl. vol. vii. p. 391.' We have four good specimens in our Museum, presented by Mr. C. Prideaux. P. depurator, the Flying Crab of fishermen. Not uncommon: we have

two specimens, obtained by the trawl, from Mr. C. Prideaux.

P. liviilus. One Plymouth specimen in our Museum, from Mr. C. Pri

deaux, by the trawl; others have been obtained by Montagu. P. emarginatus. One specimen found at Torcross ; (Leach, "Lin. Tran.'

vol. xi., and Edinb. Ency. vii., p. 390). Mr. Prideaux tells me it was

also obtained in Plymouth by Gibbs. P. pusillus. Two Devon specimens in our Museum from Mr. C. Pri

deaux. PLATYONIChus, sub-genus. P. rariegatus, (Portumnus of Leach, whose designation is changed

Cuvier, from being “ trop rapprochée du mot Portune, déjà employée."
It is said to be very common on our sandy shores ; (Linn. Trans.' xi.

314). Mr. Prideaux informs me it is found in Bigbury Bay. Section 2. Arcuata, have the shell arched anteriorly, and all the feet pointed. CANCER, sub-genus. C. pugurus, Common Market Crab. Museum of the Plymouth Institu

tion. Large quantities of these are caught in crab-baskets along our coast, from Plymouth to Torbay, the majority of which are picked up by the passing steam boats, and conveyed to Portsmouth and London

for sale. C. poressa, Oliv., (Xantho florida, Leach). Common in South Devon ;

we have several specimens. PIRMELA, sub-genus. P. denticulata. Rare; we have three specimens, sent by Mr. Prideaux

from Bantham. Mr. Couch finds them in Cornwall, though rarely. ATELECYCHUS, sub-genus. A. septemdentatus. Found frequently in Plymouth sound by Mr. Cranch,

Edinb. Ency. vii. 430. A male and female are in our Museum, sent by Mr. Prideaux. Section 3. Quadrilatera, having the carapace square or heart-shaped, with the front prolonged, inflected, and forming a sort of hood; tail of seven segments; eyes on thick pedicles. PILUMNUS, sub-genus. P. hirtellus. Obtained only in South Devon, Leach, Edinb. Ency. vii.,

391. It is rare here, we have only three specimens from Mr. Č. Prideaux, obtained at Bantham. Mr. Couch states that in Cornwall they

are frequently found in crab-pots at from 4 to 6 fathoms water. GONOPLAX, sub-genus. G. bispinosa. Abundant in Salcombe Bay (Montagu), and in Plymouth

Sound (Leach, ‘Linn. Trans. xi.) We have four specimens, and there

are others in the possession of different collectors in the town. PINNOTHERES, sub-genus. P. varians. One Devon specimen is in our Museum, found by Mr. Pri

deaux in a Cardium. T'he Pin. pisum (Mytilorum, Latr.) appears to be the female, (see ‘Dict. des Sciences Nat.' t. xxviii, 238), of which

we have four specimens. P. veterum. Of this we have one Devon specimen. Mr. Prideaux has

found them in oysters as well as Pinnæ ; the Pin. pinnæ appears to be the same, and was found at Salcombe, Devon, by Montagu and Cranch,

Edinb. Ency. vii. 431. P. mytili, (Cranchii ?). Kingsbridge, Devon; Edin. Ency., vii. 430.

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