On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 449 
articular margin is very considerably raised above the remaining portion of the 
crown. The base is thick and conforms generally to the form of the superior 
surface. About one-half the number of teeth are the reverse of the others and as 
in Cochliodonts generally, they appear to have been implanted on the opposite rami 
of the jaws to form palates suited to crush the shells of molluscs or other hard 
covering of the animals on which they fed. 
Formation and locality : Mountain Limestone, Armagh. 
Ex coll. Ear] of Enniskillen. 
Xystrodus angustus, Agass., MSS. 
(GPL INYo, inkest, 9), 2X0), 2Ail,)) 
Peecilodus angustus—L. Agassiz, 1838. ‘Rech. Poiss. Foss.,” Vol. III., p. 174, indet. 
% te C. G. Giebel, 1848. ‘‘ Fauna der Vorwelt,” Vol. L., pt. 3. p. 337, 
FF 5 H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 1022. 
; 5 H. G. Bronn, 1849. “Enumerator, Paleont.,” p. 647. 
- . J. Morris, 1854. “Cat. Brit. Foss.,” p. 340. 
55 55 F. J. Pictet, 1854. ‘Traité de Paléont.,” Vol. II., p. 270. 
Xystrodus angustus—L. Agassiz, 1859. “MSS. Enniskillen, Coll.,” 
5 os Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101. 
. As Enniskillen, 1869. ‘Cat. Types Foss. Fishes,” p. 9. 
ANISM, MORIN, \ 1876. “Cat. West. Scot. Foss.,” p. 62. 
and Robertson, 
Xystrodus angustus—J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 367. 
Peecilodus angustus | 
Teeth, triangular, cuniform, length ‘9 inch, breadth °35 inch across the posterior 
margin which is widest, the two sides converge anteriorly to an acutely-pointed, 
recurved apex. The articular margin is prominent, rounded, and has a curvature 
from front to back of considerable convexity ; the postero-lateral surface of the 
crown is depressed, slightly concave, and terminates in a slight ridge forming the 
postero-lateral margin ; the latter is straight and anteriorly curved downwards, 
posterior margin slightly sigmoidal, crown surface is similarly punctated to that 
of the previous species, though the arrangement in lines is not so clearly shown. 
Base, thin compared with that of X. striatus. 
It is possible this species may be the teeth of the upper jaw of X. striatus, both 
are found in the same beds at Armagh, but until some evidence that such was the 
relation they held is forthcoming, it may be better to regard them provisionally as 
separate species. 
Formation and locality; Mountain Limestone, Armagh. 
Ex coll, Karl of Enniskillen. 
4A2 
