154 



TELEOSTOMES 



Diplurus has become excessively shortened in its body- 

 length ; the head is of relatively enormous size ; its derm 

 bones are squamous, and appear to have been deeply 

 implanted in the integument ; teeth have disappeared ; 



Fig. 156. — Diplurus longicaudatus, Newb. X J. Triassic, Boonton, N.J. 



A. Position of calcified swim-bladder. A" . Second anal fin (now the ventral 

 portion of the functional caudal). BR. Radial and basal fin supports. C. Caudal 

 fin (degenerate). D. Hindmost dorsal fin (now the dorsal portion of the func- 

 tional cajudal). y. Jugular. 



scales have become exceedingly thin and are rarely pre- 

 served. Fin structures are apparently of a degenerate 

 character ; their cartilaginous bases, when showing, appear 



Fig. 156 A. — Undina ,^ulo, Egert. X 

 (Restoration after SMITH WOODWARD.) 



Lower Lias of Lyme Regis. 



to have become reduced to single plates, as BR ; the 

 caudal is the elongate tip of the vertebral axis ; the 

 functional caudal, now elongate and diphycercal, is formed 



