GOMPHOCERAS. 117 



2. Genus. — Gomphoceras, Sowerby. 



This genus contains fusiform or pyriform shells, with a much contracted 

 aperture* and a tapering apex. The body-chamber is large ; the other chambers 

 narrow and with simple suture-lines. The siphuncle is most frequently near the 

 ventral margin, but is occasionally subcentral. The surface is either smooth or with 

 fine transverse ornamentation. It occurs in the Silurian, Devonian, and Carbon- 

 iferous formations. The species described below are referred to it with hesitation 

 on account of the defective nature of all the specimens. 



1. Gomphoceras poculum, n. sp., PI. XI, figs. 2, 2 a, 3, 3 a. 



? 1842. Oethocebatites stjbftjsifoemis, D'Arch. and de Vern. (not Munster), 



Geol. Trans., ser. 2, vol. vi, pt. 2, 

 p. 347, pi. xxviii, figs. 2, 2 a. 



Description. — Shell conical, nearly straight, slightly constricted in the upper 

 part of the body- whorl, and then gently swollen, and beginning to taper in the 

 lower part of the body- whorl. Septal part tapering regularly ; ventral outline 

 very slightly convex, and dorsal outline very slightly concave. Septa gently 

 concave and slightly arched, rather close, not oblique. Section oval, the ventro- 

 dorsal being to the transverse diameter as 6:5. Siphuncle large, situated close to 

 the ventral margin, but somewhat on one side of the longest diameter. Surface 

 apparently smooth. 



Size. — Length 43 mm. Greatest diameter about 30 mm. (Specimen imperfect 

 and rather crusted.) 



Localities. — From Lummaton there are two specimens m my Collection. From 

 Wolborough, a very defective fragment in Mr. Vicary's Collection, and a still 

 poorer one in the Museum of Practical Geology appear to belong to the same 

 species. 



Remarks. — Only the two Lummaton specimens supply specific characters, and 

 these two fossils do not accurately agree, the swelling on the body-whorl of the 

 smaller one being rather higher up, and the constriction above it more defined 

 than in the other specimen. I think, however, that this may probably be due to 

 age, and at all events it is too slight a diS"erence to have any weight considering 

 the paucity of our material. In the most perfect of the two, the body-chamber 



