LEPIDOGANOIDEI. 



165 



continuous lines decussate with the true vertebral apophyses, 

 and cause the regular lozenge-shaped pattern so characteristic 

 of the pycnodont family.'"" 



Gemts Pycnodus. — The type-genus of the family is cha- 

 racterized by the large size of the round flat-crowned teeth, 

 which cover the broad jaws as by a pavement of from three 

 to five rows ;f at the fore-part of the jaws are two or more 

 trenchant incisive teeth both above and below. The oblique 

 inner processes of the scales appear as distinct dermal ossicles 

 decussating the neural spines in the space between the 

 occiput and the dorsal fin. 



This species of Pycnodus abound in the oolitic formations 

 above the lias : the one figured (P. rhombus, fig. 74) is from a 



Fig. 74. 

 Pycnodus rhombus (Upper Oolites). 



calcareous deposit, so charged with animal remains as to be 

 foetid, at Torre d'Orlando, near Naples. Species of Pycnodus 

 (P. cretaceous, e. g.) occur in the chalk of Kent ; and one 

 species ( P. toliapicus) has left its remains in the eocene clay 



* Proceedings of the Geological Society, May 1853, p. 276. These decus- 

 sating " pleurolepidal " lines are, however, in some genera confined to the space 

 between the skull and the dorsal fin, as in fig. 73. 



•f For the disposition of these teeth on the palate, see Owen's Odontography, 

 vol. i., pi. 34, figs. 1 and 2 ; and for their microscopic structure, ibid, p. 71, pi. 33. 



