42 4 Proceedings of the Royal Pliysical Society. 



be nothing more or less than a crushed specimen of a species 

 of Fristodus, with a more than usually mucronate apex.^ 



Peisticladodus, M'Coy. 



There can be no doubt that the specimen from Armagh, 

 in the British Museum, to which Mr J. W. Davis has given 

 the name of Carcharopsis Colei, is nothing else than a speci- 

 men of Pristicladodus dentaius, M'Coy, with the base broken 

 off. 



Chondrenchelys problematica, n.gen. & sp. 



Among the fishes from the Eskdale beds, obtained from 

 Mr Damon for the Edinburgh Museum, is one whose nature 

 is still more problematical than that of Tarrasius, which it 

 somewhat resembles in external shape. Two specimens in 

 the Edinburgh Museum have the head and tail preserved up 

 to near the termination of the latter, and of these the lengths 

 are, respectively, 4| and 7 inches. The shape of the body is 

 singularly elongated and eel-like, the head being small, less 

 than i of the total length, while a long, low, continuous 

 dorsal fin runs along the back from not far behind the head 

 to the end of the slender pointed tail. 



In the larger of these two specimens no structure can be 

 made out in the head at all, owing to the obstinacy with 

 which a layer of matrix adheres to the surface. 



The smaller affords not much more light as to this part, 

 though the shape of the head appears pointed, and there is 

 some appearance of what is either a mandible or a palato- 

 quadrate arch. It is even difficult to make out whether the 

 substance exhibited be true bone, or calcified cartilage, though 

 there is a spicular-looking body lying longitudioally in the 

 middle of the head, which from its smooth, almost glistening, 

 aspect reminds us of bone. About ^ inch behind the head, 

 and apparently not at all attached to it, is an evident 



1 My friend, Mr A. Smith Woodward, writes to me that he has, from 

 an examination of specimens from Derbyshire, come to the conchision that 

 Fristodus Benniei (R. Eth., jun.) is, after all, distinct specifically from 

 P. falcatus, Ag. Condnnus (Davis) he is also inclined to regard as distinct ; 

 and in that case all three names will stand as species of Fristod^cs. 



