80 Proceedings of the Boi/al Physical Society, 



usually listed under the name of Poterioceras (M'Coy), but 

 both the late S. P. Woodward* and Professor R J. Pictetf 

 have drawn attention to the identity of the two. The former 

 name has precedence by many years. Three species only are 

 known from the British Carboniferous, all of which are found 

 in Scotland. Only one of tliese has, so far as my know- 

 ledge of the subject goes, been discovered in the East, viz. : 

 G. ve7it7ncosum (M'Coy).;]: Another species, G. cordiformis, 

 attains a very large size, forming a fit companion for the 

 huge Actinocei^as giganteum, with which it is associated in 

 the limestone at Closeburn. § 



The Goniatites were formerly placed in the Family of the 

 Ammonitidse, but M. Barrande has shown that they differ 

 from the structure usually assigned to this group in several 

 very important particulars.il He has therefore separated 

 the genus Goniatites, and placed it in a Family by itself, the 

 Goniatitidai. Fourteen species are said to exist in the Scotch 

 Carboniferous Limestone, and form perhaps the most difficult 

 and complicated group of shells of the whole series ; more- 

 over, they are said by Messrs Armstrong and Young to be 

 usually of small size.lT 



In bringing this short and imperfect notice of the Scotch 

 Carboniferous Cephalopoda to a close, we must not omit the 

 genus Nautilus, of which nine species are known to occur. 

 These are referable to four sections of the genus. Nautilus 

 proper, Discites (M'Coy), Temnocheilus of the same author, 

 and Trematodiscus (Meek and Worthen). Discites is repre- 

 sented by N quadratics (Fleming), from various localities; 

 Temnocheilus by N. hiangulatus (Sby.) and N. glohatus (Sby.) ; 

 Trematodiscus by N. sidcatus (Sby.), and so on. A very 

 typical, and, I believe, purely Scotch Discites has been de- 

 scribed by Mr J. Armstrong as N. {Discites) nodifcrus,*'^ 

 and is almost confined to the Upper Limestone Group. 



* Man. Mollusca, p. 89. f Traite de Tal., 1854, iii., p. 644. 



+ J. Livingstone, "On Poterioceras ventricosum from the Carboniferous 

 Scries near Gorebridge " (Proc. Roy. Phys. Soc., Edinb., i., p. 470). 

 § Min. Con., iii., p. 85. 



II Bull. Soc. Geol. de France, 1856, xiii. , p. 375. 

 1 Catalogue, p. 62. ** Trans. Geol. Soc, Glasgow, 1865, ii., ]>t. ], p, 74. 



