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 }. Triassic, Boonton, N.J. 
A. Position of calcified swim-bladder. A’’. Second anal fin (now the ventral 
portion of the functional caudal). A. Radial and basal fin supports, C. Caudal 
fin (degenerate). D. Hindmost dorsal fin (now the dorsal portion of the func- 
tional caudal). ¥. 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. r56 A.— Undina gulo, Egert. xX}. Lower Lias of Lyme Regis. 
(Restoration after SMITH WOODWARD.) 
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 
