J. W. Davis— Carboniferous Fish-remains. 155 



the new Natural History Museum. From M. quadratus, Agass., this 

 species may be distinguished by its greater breadth, straight anterior, 

 and rounded posterior margins. The second tooth is readily distin- 

 guished by its form ; and both are less distinctly punctate than in 

 M. quadratus. The coronal surface of Mylacodus sesamini, Agass., 

 is uniformly rugose, and the lateral depressions near the margin are 

 deeper and more extensive. The form of the crown is that of a 

 truncated cone as compared with the broad expansion of the species 

 now described, which it is proposed to distinguish as Mylacodus 

 variabilis. 



Genus Khymodus, Agass. MS. 



Davis, Trans. Koy. Dublin Society, n.s. vol. i. p. 473. 



Bhymodus convexus, Davis, sp. nov. (Fig. 7, p. 150). 



Teeth : length 0-25 inch, breadth 045 inch. Crown, median portion 

 uniformly convex, with depression on each side, lateral extremities 

 raised into prominent ridges ; surface enamelled ; central part con- 

 siderably worn by attrition, beautifully punctate, without definite 

 arrangement. Anterior and posterior margins similar ; central part 

 rounded, with a depression, corresponding to the one across the 

 surface, on each side. Antero-lateral angles produced, slightly 

 rounded ; opposite ones similar. Base not exposed. 



This species diffei's from Bhymodus transversus, Agass., and Bhy- 

 modus oblongus, Davis, in the form of the coronal surface. In each 

 of the species named there is a decided concavity in the median part 

 of the anterior margin. In this species the anterior margin is convex. 

 The aliform processes of the crown as well as the root, which are 

 prominent in the two forms previously described, are not largely 

 developed in this species. Whilst differing in specific details from 

 the forms of Bhymodus, the transversely oblong form, prominent 

 convex crown with lateral depressions and raised margins, are generic 

 characters sufficiently distinct to leave no doubt as to its relation- 

 ship with that genus. Having reference to its especially rotund 

 coronal surface, the name Bhymodus convexus is suggested to dis- 

 tinguish the species. 



Genus Characodus, Agass. MS. 

 Davis, Trans. Eoy. Dublin Soc. n.s. vol. i. p. 474. 

 Characodus minimus, Davis, sp. nov. (Fig. 8, p. 150). 



Teeth trapezoidal in outline, small size ; anterior margin 0-2 inch 

 in length, posterior one 0-25 inch ; length 0*12 inch. Crown from 

 front to back convex ; laterally, slightly convex, the middle portion 

 worn by attrition and somewhat depressed. The surface is covered 

 with enamel, and minutely punctate where unworn. All the margins 

 are straight. The base is hidden by the matrix, but appears to be the 

 same size as the crown. 



This tooth approaches most nearly to the generic characters 

 possessed by the genus Characodus ; it differs from the species 

 hitherto described as C. angulatus, Ag., and C. cuneatus, Ag. (Fossil 

 Fishes of the Carb. Limestone Series of Great Britain, Trans. Koyal 



