PETALODONTIDiE. 
61 
Type. Detached tooth ; (?) British Museum h 
Single known species. 
Form. Sf Log. Lower Carboniferous Limestone : Armagh. 
P. 2648-9. Specimens described and figured by J. W. Davis, loc. cit. 
Enniskillen Coll. 
P. 2647, P. 2650. Four similar teeth. Enniskillen Coll. 
P. 2647 a. Naturally associated series of three teeth, showing the 
typical Petalodont arrangement. This specimen forms 
the basis of the description and figure by J. W. Davis, 
loc. cit. p. 511, pi. Ixi. fig. 4. Enniskillen Coll. 
P. 1475. Imperfect tooth. Egerton Coll . 
Genus MESOLOPHODUS, nov. 
Teeth robust. Crown relatively thick, elevated, with a sharp 
cutting-edge ; posterior face of triangular outline, with truncated 
summit, slightly hollowed mesially, and with straight inferior 
margin ; anterior face of nearly similar form and size, hut with a 
sharp vertical median ridge and W-shaped base-line. Base of 
crown with at least one large fold. Foot as deep as the crown, 
abruptly truncate. 
The supposed distinct genus represented by these teeth may 
perhaps pertain to the Petalodontidse. In some respects the teeth 
are suggestive of those named Lisgodus and Cdlopodus. 
Mesolophodus problematieus, sp. nov. 
Type. Detached teeth shown, nat. size, in PI. I. figs. 18, 19. 
Single known species. 
Form. Sf Loc. Lower Carboniferous Limestone : Armagh. 
P. 2641. Type specimens. The original of PI. I. fig. 18 is a nearly 
complete crown displaying the anterior aspect. The* 
tooth shown in PI. I. fig. 19 is nearly complete and ex¬ 
hibits the characters of the posterior aspect. 
Enniskillen Colli 
P. 2641 a. Three abraded crowns. Enniskillen Coll. 
The so-called genus Cy matodus , H. Trautschold, 1879 (non New¬ 
berry and Worthen, 1870), may also probably he referred to the 
1 An unmarked tooth in Admiral Jones’s Collection, either in the Museum 
or in the possession of the G-eologieal Society, 
