CHONETES. 191 



numbers in the Craigenglcn beds in Stirlinghire, and, as far as their position is at present 

 known, in the lowest portion of the marine limestone, or close upon the horizon of the 

 Scabricula limestone. 



We will now conclude this perhaps unsatisfactory account of the British Carboniferous 

 Chonetes by reproducing the description given by Prof. M'Coy of two very doubtful so- 

 termed species. 



Chonetes (Leptoena) serrata, M'Coy, Synopsis of the Char, of the Carb. Poss. of Ireland, 

 pi. xviii, fig. 10 (fig. 26 of my plate). 



" Semicircular, convex ; surface covered with numerous, rather coarse, branched 

 ridges ; hinge-line equal to twice the length, straight, furnished with twenty small, hooked 

 spines ; breadth ten lines, length five lines. One of the rarest fossils we have." (M'Coy, 

 p. 121.) 



Obs. I have seen the original undeterminable fragment upon which this so-termed 

 species has been fabricated, and which was obtained from the lower limestone of Millecent, 

 in Ireland. Prof, de Koninck has referred it to C. variolata, but I would not venture 

 to emit any opinion based upon such in sufficient material. 



C/ioncfes (Leptoena) inbereulata, M'Coy. Synopsis of the Characters of the Carb. Limest. 

 of Ireland, pi. xx, fig. 5 (fig. 27 of my plate). 



" Semicircular, convex ; length two thirds the width ; surface with about forty-eight 

 thick, rounded, dichotomous, smooth ribs, each bearing towards the margin a row of from 

 five to eight round tubercles. 



" This curious little species is nearly semicircular, the hinge-line being much shorter 

 than the width of the shell ; moderately convex ; the radiating ribs are thick, smooth, and 

 distinctly separated, branching as they approach the margin, where they bear a row of six 

 or eight little round tubercles. Length five lines, width eight lines." ('Synopsis,' p. 121.) 



Loc. The lower Carboniferous limestone of Millecent, Clare, Ireland. 



Obs. I am acquainted with the original specimen, which consists of a single valve, in 

 the collection of Sir R. Griffith, but upon such insufficient material would not venture to 

 pass any decided opinion as to its specific claims. 



