284 REPORT — 1844. 



bien conserves dans ces fossiles et que les squelettes mettent en evidence. 

 Pour determiner les poissons de Sheppy je devrais avoir a ma disposition une 

 collection non moius riche de squelettes demembres, de cranes detaches, d'os- 

 semens isoles. Or, une telle collection ne pent se faire que lentement et a 

 grands frais, surtout lorsque celui qui la forme vit eloign^ de la nier et n'a a 

 sa disposition qu'un petit musee destine plutot a acquerir des exemplaires 

 typiques de genres, que des series d'exemplaires de la meme espece. 



Si malgre ces difficultes je puis presenter aujourd'hui un aper9u assez 

 complet sur les poissons fossiles de Sheppy, je le dois a I'obligeance des geo- 

 logues anglais, en particulier de Lord Enniskillen, de Sir Ph. Egerton, du 

 Dr. Buckland, du Rev. M. Hope, de MM. Bowerbank, Cumberland, des 

 Directeurs du Musee Britannique, du College des Chirurgiens, &c., qui tous 

 m'ont communique a I'envi les pieces originales de leurs collections, que j'ai 

 pu de cette maniere comparer directement avec des cranes de poissons vivaus. 

 Ce travail a ainsi ete fait sur des bases toutes neuves. Les travaux des ich- 

 thyologistes anterieurs n'ont pu meme m'etre que d'un faible secours, et meme 

 les grands ouvrages d'anatomie comparee de Cuvier, de Meckel, et de tant 

 d'autres mont rarenient fourni des renseignemens suffisants, car ils ont pour 

 but de faire connaitre les os du crane et de la tete en general, d'indi- 

 quer la part que ces os prennent a la formation du squelette osseux de la 

 tete, de decrire les variations qu'ils peuvent subir en composant les types les 

 plus extravagants, et enfin de faire ressortir I'analogie des os avec ceux des 

 autres classes des vertebres plutot que d'indiquer la forme precise de chaque 

 OS dans tous les genres. II en est de meme des grandes discussions ana- 

 tomiques du commencement de notre siecle qui ont porte sur I'analogie de la 



tolerably well-preserved in those fossils, and which are exhibited by the ske- 

 leton. To determine the fish of Sheppey, I was obliged to have at my disposal 

 a collection not less rich of dismembered skeletons, detached crania, and of 

 isolated bones ; but it is only possible to form such a collection slowly and at 

 great expense, especially when the person who forms it lives at a distance 

 from the sea, and has at his disposal but a small museum, destined rather to 

 receive typical specimens of genera than series of specimens of the same 

 species. 



If, notwithstanding these difficulties, I am able to offer at present a tolerably 

 complete sketch of the fossil fish of Sheppey, I owe it to the kindness of En- 

 glish geologists, in particular of Lord Enniskillen, of Sir Philip Egerton, of 

 Dr. Buckland, of the Rev, Mr. Hope, of Messrs. Bowerbank, Cumberland, 

 the Directors of the British Museum, of the College of Surgeons, &c., who 

 have all eagerly communicated to me the original fragments from their col- 

 lections, which I have thus been able to compare directly with the crania of 

 recent fish. This investigation has thus been made on entirely new bases. 

 The labours of former ichthyologists have scarcely afforded the least assistance ; 

 and even the great works on Comparative Anatomy of Cuvier, Meckel and so 

 many others have rarely furnished sufficient information ; for their object is 

 to make known the bones of the cranium and of the head in general, to indi- 

 cate the part which these bones take in the formation of the osseous skeleton 

 of the head, to describe the variations they may undergo in composing the 

 most extravagant types, and lastly, to point out the analogy of the bones with 

 those of other classes of Vertebrata, rather than to indicate the precise form 

 of each bone in all the genera. The same is the case with respect to 

 the great anatomical discussions at the commencement of the present cen- 

 tury, which related to the analogy of the head of fish with that of the otiier 



