154 DIVISION I. VERTEBRAL ANIMALS.—CLASS IV. PISCES. 
shaped like a stiletto, and another, /s¢éophorus, has a beak like the preced- 
ine, but the dorsal fin high, serving as a sail in swimming. All of the 
eroup are of large size, and the flesh, especially that of NVphias gladius, 
is much esteemed. 
Centronotus. — This genus is distinguished by having free spines in- 
stead of the first part of the dorsal; all the species are furnished with ven- 
tral fins. The best known representative of the class is, — 
Naucrates ductor, the Pilot-fish, which has a spindle-shaped body, free 
dorsal spines, and two free spines before the anal. The South American 
black species attains the enormous length of eight or nine feet. The Med- 
iterrancan Pilot-fish does not exceed a foot in length, but is an extremely 
swift and voracious animal, following in the wake of ships, accompanied by 
sharks, which it was formerly supposed (erroncously) to lead, whence its 
name. The following sub-genera are, — 
Helacates, form and dorsal spines like the last, but the head flattened, 
and the keel and anal spines wanting. 
Lichia, has dorsal and anal spines on the back, one of the former lying 
flat and direct forwards, but the body is compressed, and no keels on the 
tail. There are several species in the Mediterranean, all eatable, and some 
of large size. Trachinotus, merely has the body a little more elevated, and 
the dorsal and anal longer and more pointed. 
RiyNcuoppeLLa. —In their spinal structures the fishes of this group 
resemble the former genus, but have no ventrals. The sub-genera are, — 
Mucroguathus, with a pointed, cartilaginous muzzle, projecting beyond 
the lower jaw, and the dorsal and anal separate from the caudal. JZes- 
tacenbelus, jaws equal, and dorsal and anal joined to the caudal. Both 
inhabit the fresh waters of Asia, and feed on worms, in search of which 
they plough up the sand with their cartilaginous noses; their flesh is much 
esteemed. 
Noracontiuus. — The waters of the Arctic Ocean are the home of this 
genus, where individuals are sometimes found- two feet and a half long. 
They have a pointed, cartilaginous muzzle, abdominal ventrals, and a long 
anal reaching to the top of the tail. } 
SeRIOLA. — This genus resembles lichia, has a horizontal spine before 
the dorsal, but the dorsal spines united by a fin, a small fin with two spines 
before the anal, and no keel on the lateral line. One species is the Milk- 
fish of Pondicherry, so much esteemed for the delicacy of its flesh. There 
are several other species in both oceans. 
Nomews, resemble the last, but have large ventrals attached to the abdo- 
men by their inner edge; color, silvery, with transverse black bands on the 
upper part. Has been confounded with the gobies. 
