450 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
Xystrodus egertoni, Davis. 
(Pl. LV., figs. 22, 23, 23a.) 
Palatal teeth more or less rhomboidal and angular in outline, 1‘1 inch in length, 
‘4 inch in breadth towards the posterior portion. Anteriorly the teeth are slightly 
convoluted with a broad termination. The articular margin is thick, prominent, 
and elevated above the remainder of the crown, the remaining portion of the crown 
is flat with a very slight concavity, posterior portion of surface much depressed ; 
posterior margin forms an oblique angle with the margin of the articulating ridge. 
Surface, closely covered with raised pustules, occasionally exhibiting a slight 
tendency to arrangement in rows, the anterior part of the crown where most worn 
exhibits a punctate surface as though the pustulated surface had been ground down 
and a section of the dentigerous tubes exposed. Base very thick. 
This species is at once distinguished from those collected at Armagh by the 
angularity of its proportions and the very slight concavity of its coronal surface. 
I have indited it to the memory of the late Sir P. Egerton, whose researches in’ 
fossil ichthyology will ever serve as a fitting monument to his learning and a model 
on which to base future investigations. 
Formation and locality : Mountain Limestone, Bristol. 
£2 coll. Earl of Enniskillen. 
Xystrodus pulchellus, Davis. 
(Pl. LV., figs. 24, 24a.) 
Teeth, small, triangular, length °3 inch, anteriorly pointed, expanding posteriorly 
to 15 of aninch. Surtace of crown, concave, rising laterally to form a strong 
rounded ridge on one margin whilst the opposite one is depressed towards the 
anterior extremity, but is raised slightly towards the posterior surface. Base 
hidden. Coronal surface, beautifully marked by a series of transverse ridges 
parallel to each other extending over the raised lateral ridge and disappearing as 
they descend to the concave surface, which is smooth. On the opposite margin 
there is a row of minute denticulations. The whole is uniformly and minutely 
punctate, ; 
This interesting little species is found in the limestone of Wensleydale, and 
appears to be quite distinct from the species found at Bristol and Armagh. 
Formation and locality: Carboniferous Limestone, Wensleydale. 
Ex coll, Reed Collection, York Museum. 
