VERTEBRATES. 361 



There is no doubt of the affinity of the fish that bore these teeth with Oro- 

 dus, but the differences which have been indicated seems to us of generic value. 



Orodus has, up to the present time, not been found in strata more recent 

 than the Lower Carb. limestone, and we may regard Lophodus as the represen- 

 tative of that genus in the fauna of the Coal Measures. 



LOPHODUS VARIABILIS, N. and W. 



PL iv, figs. 4, 4a, 46, 5, 5a, 11, lla, 116. 



TEETH of medium size, of three or more forms ; largest and 

 central? teeth (fig. 11) having a V shaped base, on the angle of 

 which is set an ovoid or conical, laterally compressed crown 

 which bears on the medial line a sharp, serrated crest, passing 

 from the base on the anterior face over the crown to the base 

 on the posterior face. On the anterior side the crown is con- 

 stricted at its juncture with the base. On the posterior face 

 it is supported by acute crested buttress-like wings, which run 

 down to the lateral prolongations of the base. The base is 

 vertically flattened under the wings of the crown, thicker and 

 conical before, somewhat pitted and roughened. Other teeth 

 of the series are transversely elongated laterally, somewhat 

 arched backward at the extremities. The crown has a gen- 

 eral conical outline with a pectinated crest along the most ele- 

 vated line. Transverse crests cross the central summit and 

 two lateral eminences from front to rear. On the posterior 

 face the central and lateral eminences form strong ridges 

 which give the tooth a peculiar yoke-like plan. 



The third form of tooth (fig. 5) is still more elongated laterally, having the 

 form of some species of Orodus. The crown is marked by a central or sub- 

 central prominence, on either side of which are several minor summits which 

 may be said to be formed by projecting rings arching over the crown from 

 front to rear. The root is vertical, flattened, pitted or vernacularly marked, 

 and bevelled on the lower edge. Like the others, these teeth are ornamented 

 by pectinated ridges along the line of greatest elevation, and transversely on 

 the more prominent points. 



The enamelled surface of the crown in all these teeth is highly polished, and 

 46 



