OEDEES OF FISHES. 



137 



and Sir Philip Egerton, the articulation of the scales, instead 

 of being by pegs and sockets, as in Dcqjcdius, rather re- 

 sembles that of the " Pycnodonts," to ^vhich the genus is 

 very closely allied. Each scale, namely, bears upon its 

 inner anterior margin a thick, solid, bony rib, extending 



Fig. 503. — Bapedius (^chmodus), restored. Lias. 



upwards beyond the margin of the scale, and sliced off 

 obliquely above and below, on opposite sides, for forming 

 splices with the corresponding processes of adjoining scales. 

 The Lepidotidce have a homocercal tail (fig. 502, 3), and 

 possess obtuse teeth. The type -genus, Lcpidotus, ranges 

 from the Lias to the Eocene Tertiary. The Lcptolepidcc 

 (fig. 502, 2) have also a homocercal tail, and possess small 

 rounded scales. The species of this family are all Secondary 

 in their distribution. 



According to the researches of Traquair, the well-known 

 group of Secondary fishes comprised under the name of 

 Pycnod.ontidcc, should really be placed under the Lepidosteids, 

 rather than with the Flatysomidce, as has usually been done. 

 In this group the body is rhomboidal and compressed, and 

 covered with rhombic scales, while the teeth are characteris- 

 tically blunt and rounded. In the true Pycnodonts the teeth 

 (fig. 504) are multiserial, and are adapted for crushing; 

 consisting of " a circular or transversely oval crown. Battened 

 above, and sessile on the bone to which it is attached ; or 

 of an obtusely conical crown, which is broader than its 

 peduncle of support " (Young). There are typically five 

 rows of teeth on the vomer, while the lower jaw carries a 

 corresponding series of three, four, or five rows of dental 



