432 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
Teeth, “ Wing-shaped or contorto-subtrigonal, narrow before, broad and sub- 
truncate behind, inner straight margin thin, higher in the middle than atjeach end ; 
the surface seeming concave from thence to the external oblique margin, which is 
abruptly deflected, much thickened, rounded, strongly arched downwards at each 
end, with a slight sigmoidal curve ; this ridge is crossed by seven or eight large 
obtusely rounded wrinkles, which become obsolete as they approach the thin inner 
margin—surface finely granuloso-punctate under the lens.” (M‘Coy). 
A single specimen described by Prof. M‘Coy is in the Woodwardian Museum, at 
Cambridge ; it is the sane which is figured in the British Palzeozoic Fossils, Pl. 3 G., 
fiz. 10. So far as I know there is no other specimen of the same species. It bears 
a considerable generic resemblance to Deltodus (formerly Peecilodus) sublevs, 
though differing considerably in details. It is apparently of the same genus, and 
I have therefore transferred it from Peecilodus to Deltodus, retaining Prof. 
M‘Coy’s specific name. Its strong sigmoidal contortion and the great size of the 
transverse waves or wrinkles, distinguish it from Deltodus sublevis, Ag. 
Formation and locality: Black Upper Limestone of Derbyshire. 
Ex. coll. Woodwardian Museum, Cambridge. 
Genus.—Deltoptychius, Agass., MSS. 
Cochliodus— LL. Agassiz, 1838. “ Poiss. Foss.,” Vol. I11., p. 174,’ indet. 
Cochliodus— FF. M‘Coy, 1855. “ Brit. Paleoz. Foss.,” p. 621, pl. 3 L, fig. 24. 
Deltoptychius—L. Agassiz, 1859. “ MSS. Enniskillen Coll.” 
Palatal teeth of medium size, oblong or triangular in outline. Posterior 
margin widest, diminishes in breadth forwards. Anterior, spirally convo- 
luted. Crown, convex, raised with three more or less prominent ridges which 
expand radially from the incurved anterior extremity ; posterior margin convex, 
antero-lateral margin inrolled backwards, median margin thick, convoluted back- 
wards. Surface minutely pustulate ; where worn it presents a punctate appear 
ance. Base thick and strong, concave. 
The teeth comprised in the genus Deltoptychius were originally considered by 
Prof. Agassiz to be a species of Cochliodus, and were named by him Ccchhodus 
acutus (“ Poiss. Foss.,” Vol. IIT., p. 174), but were not described. Prof. M‘Coy, 
accepting Agassiz’s definition, described and figured the specimens as C. acutus 
(“ Brit. Paleeoz. Foss.,” p. 621, Pl. 3 I., figs. 24, 25, and 26). The two first figures 
are those of the teeth of the lower jaw (those called posterior teeth) ; they exhibit 
very imperfectly the convoluted, almost helicine infolding of the anterior portion 
of the tooth. | 
The tooth of the upper jaw (anterior of M‘Coy), represents a very small and 
imperfect specimen. In all the collection which forms the subject of the following 
