On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan. 497 
Petalodus recurvus, Davis. 
(ER IDXer stro 23) 
Teeth, medium size. Crown, very broad, nearly twice the breadth of the base as 
well as of its length ; anterior face, laterally circular, vertically concave; apex, 
circular, minutely serrated, sharp; coronal ridge prominent, with two or perhaps 
three somewhat indistinctly imbricated folds of ganoine. The width of the crown is 
14 inch, greatest height in centre °35 of an inch ; from the centre, the coronal ridge 
by a sigmoidal curvature, approaches towards the apical circumference, the lateral 
extremities are curved considerably towards the base and end in an acute point. 
Posterior surface not visible, embedded in matrix. Root, rapidly contracted from 
the width of the crown to one half its diameter, it is 4 inch in length, roughly 
fibrous, convex, laterally depressed. 
This species is marked with considerable distinctness from any other British 
species, neither does it approach near to any of the American forms. It differs from 
P. acuminatus, Agass., in its greater breadth of coronal surface compared with its 
depth, the roundness of the cutting edge, which in P. acuminatus is pointed in the 
centre. The crown is also much less pointedly produced along the anterior median 
ridge. The root is shorter, thicker, and has a circular termination. 
In general form this species is similar to P. linguafer N. and W. (“ Paleeon. Hhinois,” 
Vol.IL., p. 37, pl. ii., figs. 4, 5), but may be easily distinguished by the lateral extremi- 
ties of the crown, which in this species are curved towards the basal portion and 
acuminate, whilst in P. linguifer they are rounded and terminate without curvature 
towards the base. 
Formation and locality : Mountain Limestone, Bristol. 
Ex colt. Ear] of Enniskillen. 
Petalodus inequilateralis, Davis. 
(Pl. LX., figs. 3, 4.) 
Teeth, length 1:2 inch, height 55 inch; coronal surface, broad and short, 
indefinitely sinuous. Base nearly as wide as crown and twice its depth. Crown, 
anterior surface, expanded on one side the median line to twice the height of the 
opposite one. The wider half terminates in a rounded extremity without 
depression, whilst the narrow one is curved towards the base and terminates 
acutely. Cutting edge, generally much worn or minutely serrated. Coronal ridge 
somewhat prominent, bearing three or four imbricated ganoine folds, extending 
across the tooth with a doubly sigmoidal curvature. Posterior surface, deeper 
than the anterior, but taken up in great part by eight or ten foldings of the surface, 
go that the smooth portion is less in vertical extent than that of the anterior 
surface. The form of the posterior portion of the crown conforms generaily to 
that of the anterior one, at the broad end its height is °35 inch, at the narrow one 
4G2 
