UERCETIDJE. 
171 
and there are no traces of transverse processes. The 
neural spines, ribs, and intermuscular bones are shown as 
in the previous specimen, and the characteristic dorsal 
fin-supports occur, without any traces of the fin itself. 
Remains of the clavicle and supraclavicle occur; and the 
longest rays of the pectoral fins are about half as long 
as the head with opercular apparatus. No scales can be 
distinguished. Lewis Coll. 
49522. See p. 182. 
Family DERCETIDiE. 
Head and trunk much elongated. Parietal bones of moderate 
size and meeting in the middle line ; squamosal suturally united 
w ith parietals and completely covering the otic region ; snout con- 
siderably produced ; cheek-plates delicate or wanting. Mandibular 
suspensorium vertical or inclined backwards, and gape of mouth 
ver } wide ; premaxilla delicate, extending in front of the ethmoidal 
legion, and apparently forming the greater part of the upper border 
°fthe mouth; teeth conical and slender, in a single series on the 
m argin of the jaws, clustered on the pterygoid arcade and the inner 
side of the mandible. Opercular apparatus complete, with few 
slender brauchiostegal rays, but no gular plate. Yertebral centra 
ln file form of delieato constricted cylinders pierced by the noto- 
chord ; ribs long and slender, borne by laminar transverse processes ; 
neural and haemal spines in the caudal region very short. Inter- 
muscular bones present. Fin-fulcra absent; fin-rays bifurcated 
slightly and articulated at wide intervals in the distal half ; post- 
temporal bones in contact w'ith (ho supraoceipital, and pectoral fins 
low down upon the flanks ; pelvic fins well-developed, abdominal ; 
a single dorsal fin, more or less extended; anal fin short ; caudal 
fin separate. Ordinary scales small or wanting, but two or more 
continuous paired series of enlarged scutes along the flanks ; no 
median dorsal or ventral scutes. 
Synopsis of Genera. 
I. ISo scales between scutes. 
Dorsal fin occupying the greater part 
of tho back, and anal fin opposed 
to its hinder portion ; scutes much 
expanded Dercetis (p. 172). 
Dorsal fin not occupying more than 
one third of the back, and anal 
fin behind it ; scutes not much 
expanded Leptotrachelus (p. 173). 
