[ 409 ] 



XXXII. — Letter from Mr. James de Carle Sowerby to the Secretary ^ 

 on the Genus Crioceratites and on Scaphites Gigas. 



[Read March 8th, 1837.] 



Dear Sir, 



XHE recent discovery in the Isle of Wight, by Mr. Bowerbank, of a fossil 

 shell resembling- Ammonites, but differing essentially from that genus, and 

 of a magnificent Scaphites, appears to me of sufficient importance to be laid 

 before the Geological Society ; I have, therefore, drawn up the following- 

 descriptions, accompanied by reduced figures of the fossils*. PI. XXXIV. 



Crioceratites. 



Generic Characters. — An involuted chambered shell, with sinuated septa ; the whorls free, 

 sometimes very distant. Siphon in the external margin of the septum. 



The genus is distinguished from Ammonites by the whorls not uniting or 

 closing upon one another, or making even an impression, except towards the 

 centre of the disc, and not there in all species. From Scaphites it also differs 

 in not having the last whorl produced and bent like a hook ; this whorl is 

 often marked diff'erently from those which precede it in both genera. 



Many of the shells to be grouped in this genus have hitherto been considered 

 Hamites. The species to which I allude are Hamites Beanii, H.plicatilis, and 

 H. intermedins^, of Phillips (Geol. Yorks., Pt. I , PI. 1., figs. 28, 29, 22.), 

 Hamites rotundus, (Min. Con., PI. 6 1.), H. spinulosus, H. spiniger, H. tuher- 

 culatus, H. nodosus, and H. turgidus, of Mineral Conchology (PI. 216.). 



• These fossils I was induced to consider as belonging to an undescribed genus, for which I 

 proposed, in my communication to the Society, the name of Tropceum : since that notice was read, 

 I have seen in the second part of the second volume of Memoirs of the Geological Society of 

 France, published in March, 1837, M, le Ch. Leveille's description of his new genus Crioceratites, 

 which proves to be identical with Tropceum. As M. Leveille's paper must have been read before 

 my letter, it is clear that the name Crioceratites must be employed in place of Tropceum, and it is a 

 very good name. The circumstance of a foreign autlior having distinguished the genus goes far 

 to prove the propriety of its being established. Two of Leveille's species occur in the Speeton 

 Clay of Yorkshire. One of them, C. Emeritii (Loc. Cita. PI. XXIIL, f. 1.), is Hamites Beanii, of 

 Phillips, PI. L, f. 28, the other, C. Honoratii (Loc. Cita. PI. XXIL, f. 2), is not yet published by 

 any English author, but has been called H. plicatilis, although distinct from the species so named 

 in the Mineral Conchology (PI. 234.).— Dec. 1837. 



■j- I strongly suspect this is not H. intermedins of Min. Conch. (PI. 62.) 



