230 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



are found also associated with Ammonites and Belemnites in the 

 lithographic stone quarries of Germany. The species appear all 

 to be new. 



Ganoid Order. 

 Lepidoid Family. 



Lepidotus macrochirus, Eg. 



I have only seen one specimen referable to the genus Lepi- 

 dotus ; it is, however, the finest ichthyolite yet discovered in this 

 locality. The fish reclines on its back, and presents the whole 

 ventral surface to the spectator. The head bones are rather dislo- 

 cated, by which accident an advantageous view of the teeth is ob- 

 tained. The two large bones of the horns of the hyoid bone are 

 seen in situ. The pectoral and ventral fins are well displayed ; 

 the anal and caudal are crushed and indistinct. As compared 

 with the species of this genus already described by Agassiz, this 

 Lepidotus has the nearest affinity to Lepidotus semiserratus of the 

 Whitby lias : it differs in the narrowness of the head, the larger 

 size of the pectoral fins, and the marginal armature of the scales. 

 The form of the lower jaw is well shown. The teeth are numer- 

 ous, both in the upper and lower jaws, as also on the palate ; they 

 are in the form of acute cones, on constricted pedicles. The teeth 

 on the palate are larger than those on the maxillary bones. The 

 pectoral fins are large and strong. The rays are twenty or twenty- 

 one in each fin, single for about half their length, then articulated ; 

 the articulations being frequent, and the ossicles small. The rays 

 dichotomize so frequently as they recede from the base, that the 

 extremity of the fin has a finely fimbriated appearance. The 

 ventral fins are small, but the rays composing them are strong, 

 apparently about eight in number. The scales have the thick 

 enamelled surface so characteristic of the genus. The posterior 

 edges of the flank scales are deeply notched or scalloped ; this 

 feature is traceable in other parts, although the number of notches 

 in the caudal region is reduced to two or three. The gradual 

 change of outline from the oblong to the lozenge shape as the scales 

 approach the belly and tail, obtains as in other species of this 

 genus. The arrangement of the scales of the vent has not hitherto 

 been described in this genus. Indeed, no specimen with which I 

 am acquainted, exhibits these details ; and yet we can scarcely 

 imagine them peculiar to the species under description, but as 

 common to the genus. In front of the anal fin, we find a pair of 

 scales of large size ; these are overlapped by a single scale con- 

 siderably larger, and the anal orifice is situate under the middle of 

 the posterior edge of the latter, coincident with the line of junc- 

 tion between the former. These three scales are quadrangular, and 

 deeply notched on their free margin. Having had only a brief 

 opportunity of examining the specimen above described, the details 

 are not so complete as I could wish ; they are, however, sufficient 



