On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 519 
and is described as holding a similar relationship to P. pseudosagittatus that P. 
psittacinnus does to P. sagittatus in the Carboniferous Limestone of Armagh, which 
may be correct. 
Formation and locality : Mountain Limestone, Armagh. 
Ez coll, Kavi of Enniskillen. 
Genus.—Pristodus, Agass. (MSS.) 
Diodontopsodus.— Davis, 1881. “ Rept. Brit. Assoc.,” 1881, p. 646. 
Teeth, medium size, beak-shaped, with a semicircular trenchant cutting edge, 
upper jaw deeply serrated; crown consists of a vertical surface enveloping the 
jaws externally, deep anteriorly and diminishing in size posteriorly on each side; 
at right angles to the vertical portion, an expansion of the bony surface forms a 
palate, extending backwards to a line with its two latero-posterior extensions, 
junction of surfaces produced to form a more or less acute cutting edge. Surface 
enamelled, smooth or slightly punctate. 
Pristodus faleatus, Agass. (MSS.) 
2, IDI, stags, 17%, IME, UG), BAO, Ail, 224) 
Pristodus faleatus—L. Agassiz, 1859. “ Enniskillen Coll. MSS.” 
e 55 Morris & Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101. 
na a Enniskillen, 1869. “Type Specimens of Foss. Fishes,” p. 7. 
3 3 J.J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 363. 
Teeth. Two forms; in those of upper jaw the cutting edge is largely extended 
and divided into a series of ten to fourteen deeply cut serrations, largest in the 
centre and diminishing in size backwards. ‘The denticles are triangular in outline, 
broad at the base, converging to an acutely pointed apex. In each example the 
centre of the tooth, which envelopes the whole external surface of the jaw, is the 
line of division between the two largest serrations, one extending on each side ; in 
no instance does one of the denticles occupy the median line. ‘The vertical length 
of the tooth is ‘5 inch from the upper palatal portion to the extremity of the 
serrated cutting edge. It is semicircular in outline, diminishing in height post- 
eriorly, and the cutting edge extends obliquely forward from above downwards. 
The lower jaw was enveloped in a somewhat similar bony investment, but whilst 
in the upper jaw the serrated cutting edge extended from the palatal surface and 
formed a long cutting edge, in the lower jaw the cutting edge is not serrated and 
extends cnly a short distance beyond the horizontal palate. It is produced and 
pointed in the centre, in the form of a beak, from which the surface of the crown 
descends on each side, forming only a slight ridge towards the posterior portions of 
the tooth. The vertical portion of the lower tooth is slightly convex, its lower 
margin extending downwards in front of the jaw, forming an acute point, and from 
TRAYS. ROY. DUB. SOC., N.S., VOL, I. 4K 
