On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 427 
the species already described by its crown being divided into two principal parts, 
a broad posterior ridge and anteriorly a wide sulcus or concave depression bounded 
anteriorly by a well-defined ridge. The intermediate ridge, present in both the 
species, S. oblongus and JS. colei, in this species 1s absent. 
Formation and locality ; Mountain Limestone, Bristol and Hook Point, County Wexford. 
Ex coll. Ear] of Enniskillen. 
Genus.—Deltodus, Agass. MSS. 
Peecilodus—L. Agassiz, 1838. <“Poiss. Foss.,” Vol. III., p. 174, indet. 
5 FEF. M‘Coy, 1855. ‘Brit. Paleoz. Foss.,” p. 640. 
Deltodus —L. Agassiz, 1859. MS. Enniskillen Coll. 
Newberry and 
2? Worthen, 
Teeth, of varied form and size depending on their position in the upper or lower 
1866. “Paleont. Illinois.” Vol. II, p. 95. 
jaw, possessing the following generic characters respectively : — 
Upper jaw. “Teeth of medium or large size, thick and strong, triangular in 
outline, more or less arched, sometimes enrolled in the line extending from the 
longest and most acute angle to the opposite margin ; crown-surface sometimes 
simply arched, more generally marked by 1-3 prominent ridges, running from the 
basal margin towards the longest angle. In some species the triturating surface 
is also undulated by a series of transverse obtuse ridges, parallel with the basal 
margin, and mostly confined to the basal portion of the tooth. The crown surface 
is uniformly punctate, the size and form of the pores varying in the different 
species. —(Newberry and Worthen.) 
Lower jaw: probably three teeth on each side. Posterior tooth, large, more 
or less quadrilateral in outline, thick and strong, prominent convexity occupies 
greater portion of crown surface, depressed on the internal lateral area forming 
an aliform expansion, Anterior margin curved sigmoidally, laterally straight, 
converging backwards forming a subtruncate, recurved posterior extremity. 
Second or median tooth: much smaller than the first, triangular in form, 
convoluted posteriorly ; convex with a median ridge ; anterior margin circular, 
laterally straight, converging backwards to an obtuse point. 
Third or anterior tooth: small, triangular, expanded anteriorly ; rapidly con- 
tracted backwards, prominent ridge extends across the tooth from front to back 
with a wide expansion of the coronal surface towards the antero-lateral angle. 
In some species the teeth are marked by transverse imbricating folds or 
ridges, which may extend parallel with the anterior margin, over a part or the 
whole surface of the tooth. 
The palatal teeth included in this genus were originally placed by Prof. 
Agassiz amongst the genus Peecilodus as two species P. sublevis and P. parallelus ; 
they were, however, neither described nor figured. Prof. M‘Coy described and 
figured the specimens as named by Prof. Agassiz in his work on the British 
Paleozoic Fossils. He considered that the triangularly oblique aod aliform 
