626 J. W. DAVIS ON REMAINS OF FOSSIL FISHES 
This differs from the anterior tooth of P. Jonesii, Ag., in haying 
the surface raised only into four folds; the latter has eight. It 
has also a much flatter and more even surface. 
Genus Sanpatopus, Newberry and Worthen, 
Geol. Surv. Illinois, vol. 1. p. 102 (1866); Davis, Trans. Roy. 
Dubl. Soc. n. s. vol. 1. p. 486 (1882). 
SANDALODUS MINOR, Davis, sp.n. (Plate XXVI. fig. 17.) 
Teeth. The specimen apparently consists of two teeth in natural 
position. Anterior tooth 0-6 inch in length and 0-25 inch across. 
It is widest posteriorly, gradually narrowing towards the an- 
terior extremity to form an obtusely pointed angle. External 
margin convex; internal one slightly concave. The posterior 
margin is thin, with a circular outline, and overlaps a second tooth, 
which extends 0-2 inch backwards, and is quite as wide as the 
anterior one. The surface of each tooth is longitudinally and 
transversely convex, with an abrupt depression on the inner margin ; 
anteriorly it is somewhat conyoluted after the manner of the less 
inrolled Cochliodonts. The surface is deeply punctate, the pittings 
presenting a slightly quincuncial arrangement. The base is 
hidden in the matrix. ; 
This tooth, though small, possesses all the characters of Sanda- 
lodus, a genus instituted by Messrs. Newberry and Worthen in 1866. 
A species of large size has been added to the genus from the 
Mountain Limestone of Oreton, in Shropshire, viz. S. Morrisiz, 
Davis (Trans. Roy. Dubl. Soc. n. s. vol. 1. p. 437, pl. liv. figs. 1-6). 
The specimen described above is not so deeply convoluted as those 
of the larger species, and its apparent division into two parts is 
peculiar. 
Genus LopHopus, Rowanowsky, 
Bull. d. 1. Soc. Impériale des Naturalistes de Moscou, p. 160 (1864) ; 
Davis, Trans. Roy. Dubl. Soc. n. s. vol. i. p. 403 (1882). 
LopHopus ReETicuLatus, Davis, J. ¢. p. 407, pl. li. fig. 22 (1882). 
(Plate XX VII. fig. 2.) 
This species is found more frequently than any other in the beds 
of limestone near Leyburn, and offers considerable variation from 
the type. In some examples, the arrangement of the coronal 
prominences is modified so that all the cones are on one side of 
the principal one; whilst in others there are no distinct pro- 
jections, the cones only being indicated by a slight waviness of the 
superior surface of the crown. The anterior base of the crown 
is occasionally expanded much beyond the extent of an average 
specimen, preserving, however, its reticulate surface-markings, 
The tooth mentioned above as almost devoid of cones is, on the 
