244 R. Etheridge, jun. — New Carboniferous Fossils. 



The crenulate striations along the cutting edge of the tooth are 

 also continued along the edges of the central denticle. 



Locality. — Shiells Quarry, near East Kilbride, Lanarkshire, from 

 shale connected with the main Limestone, Lower Carboniferous 

 Limestone Group. Collected by Mr. James Bennie, after whom the 

 species is named, and to whom I am indebted for an opportunity of 

 describing it. 



Genus Petalodus. 

 Petalodus ? lobatus, sp. nov. Plate VIII. Figs. 5 and 6. 



Sp. cJiars. — Tooth small ; crown thin, flattened ; superior margin 

 with an angular outline, gradually sloping away to the lateral angles, 

 and divided into numerous lobes or denticles, of which the middle 

 one is the largest (the sides of the specimen are broken, but on one 

 side the central denticle there are six perfect, and the remains of a 

 seventh broken denticle, whilst on the other side there are only three 

 preserved) ; surface of the crown smooth, and highly polished ; 

 anterior face convex, with the coronal ridge formed of three or more 

 imbricating bands or folds, extending from the lateral angles of the 

 tooth in a graceful curve to a central point about opposite the large 

 middle denticle of the cutting edge. Posterior face a little concave, 

 with the coronal bands more strongly marked, wider apart, more 

 numerous, and further from the cutting edge than on the anterior 

 face. The lobes into which the cutting edge is divided diminish 

 successively in size from the central large one to the lateral angles ; 

 the former is acute and pointed, the latter are bluntly rounded, and 

 all are entire and non-serrate. The root is long and pointed ; on the 

 anterior side convex in the middle, concave at the sides. 



Obs. — This elegant little tooth appears to partake in some respects 

 of characters appertaining to the genera Petalodus and Ctenoptychius. 

 It resembles the former in the arched form of the cutting edge of the 

 crown, acute lateral angles, and in the arrangement and degree of 

 development of the imbricating bands forming the inferior margin 

 of the crown, especially in those of the posterior face descending 

 lower than those of the anterior, but in the deep lobation of the 

 cutting edge approaches the latter, especially the tooth known as 

 C. serratus, Owen, 1 in which, however, each lobe or denticle is 

 serrated, whereas in the present species they are all entire. It is in 

 this lobation that P. lobatus departs from the Petalodus type ; for 

 in the species comprised in this genus the cutting edge appears to be 

 entire and merely serrate or crenate, not lobed. P. lobatus has a general 

 resemblance to Ctenoptychius apicalis, 2 Ag., but in this species, as 

 figured by Agassiz, the denticles are larger and the general form of 

 the tooth is different. A species described by Messrs. Newberry 

 and Worthen, from the Coal-measures of Indiana, as C. semicircu- 

 laris, 3 is very nearly allied to our fossil, but the section is semi- 

 circular, the lobes or denticles less in number, and either acute or 

 rounded in outline, whereas in P. lobatus they are all, with the 

 exception of the central one, rounded, and are more numerous. The 



1 M'Coy's Brit. Pal. Foss. p. 636, t. 31, figs. 21, 22, and 23. 



2 Poiss. Foss. Atlas iii. t. 19, figs. 1 and la. 



3 Geol. Surv. Eept. Illinois, vol. ii. p. 72, t. 4, figs. 18 a. and b. 



