XXXII.— Letter from Mr. James de Carle Sowerby to the Secretary, on the Genus Crioceratites and on Scaphites Gigas.
1840; Geological Society of London; Volume: 5; Issue: 2 Linguagem: Inglês
10.1144/transgslb.5.2.409
ISSN2058-1041
Autores Tópico(s)Cephalopods and Marine Biology
ResumoDear Sir, The 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*. Pl. XXXIV. 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 differently 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. intermedius †, of Phillips (Geol. Yorks., Pt. I, Pl. 1., figs. 28, 29, 22.), Hamites rotundus , (Min. Con., Pl. 61.), H. spinulosus, H. spiniger, H. tuberculatus, H. nodosus , and H. turgidus , of Mineral Conchology (Pl. 216.). If we arrange the genera of concamerated cephalopods, furnished with a siphon, and with sinuated edges to their septa, according to the straightness or degree of curvature of the shell, we shall have them in the following order,
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