Percesoces and Rhegnopteri 22.5 
sometimes longer than the body. Two of the actinosts of the 
pectoral support the fin, one is slender and has no rays, while 
the fourth is plate-like and attached to the coracoids, support- 
ing the pectoral filaments. The body is rather robust, covered 
with large scales, formed much as in the mullet. The lateral 
Fig. 178.—Shoulder-girdle of a Threadfin, Polydactylus approximans 
(Lay & Bennett). 
line extends on the caudal fin as in the Sctenide, which group 
these fishes resemble in many ways. The mouth is large, 
inferior, with small teeth. The species are carnivorous fishes 
of excellent flesh, abounding on sandy shores in the warm 
seas. They are not very active and not at all voracious. The 
Fic. 179.—Threadfin, Polydactylus octonemus (Girard). Pensacola. 
coloration is bluish and silvery, sometimes striped with black. 
Most of the species belong to the genus Polydactylus. Poly- 
U—I5 
