NATURAL HISTORY. 
141 
ROOM IV.] 
The third group differ from the former in the rays of the first dorsal 
fin being separate and isolated spines. The Pilot Fish {Pilotes) 
has a keel on each side of the tail. The Elacates are oblong fish, 
without any keel on the side of the tail. The Lichia are compressed 
with a swollen profile ; their two anal fins are continued. The Tra- 
chinotus only differs from the last in the muzzle being blunt. The 
Chorinemi differ from the two preceding in the rays of the anal and the 
second dorsal fin being separate. The Apolectus has the ventral fins 
placed on the throat. The Notacanthus has the ventral fins behind 
the pectoral; they have no second dorsal, and a long anal fin united to 
the caudal. The Rhyncobdella are elongated subcylindrical fish, with¬ 
out any pectoral fins, with a concave muzzle. The Masticetus differ 
from the latter, in having a conical muzzle. The Spicklebacks ( Gas- 
terosteus) differ from all the former in the bones of the pelvis being 
united to the enlarged bones of the humerus, forming a kind of bony 
corslet; their ventrals are placed behind the pectorals, and reduced to a 
single spine. The Sea Spicklebacks ( Gastrus) have the lateral lines fur¬ 
nished with scales and the ventral has two small rays besides the 
spine. 
The family of Zeid^e are very like the former, but the bodies are very 
high and compressed, and the mouth has a few small erect teeth; the 
scales are very small and satin-like. The mouth of the Zei are pro¬ 
tractile, and of the Stomatei are not so. The Coryphcena have ra¬ 
ther larger scales, seven gill rays, and large dorsal fin. 
The family of Gymnetrim: have an elongated body covered with 
minute satin-like scales; they have a very long ventral fin, and the 
caudal fin is placed on the upper side of the tail. 
The family of Theutides (Theutid^:) combine with the small scales 
of the Scomberoid Fish the form and small mouth of the Cheetodon, but 
are furnished with a single row of teeth with cutting edges, and their 
fins are not scaly. They live on fuci and other marine vegetables. Se¬ 
veral of the genera have sharp retractile spines on the sides of the tail, 
which v 7 hen drawn back are received in a groove, and from the w’ound 
they inflict they are often called Lancet Fish, or Surgeons. The Mo- 
noceros ( Naseus ) has the spines on the sides of the tail fixed and blunt 
and the front part of the head produced into a horn. 
The family of Pipe Fish ( Syngnathhle) differ from most other fish 
in their gills being divided into little tufts, placed by pairs on the bony 
branchial arches, instead of being formed of regular pectinated plates. 
Their body is also covered with shields, w T hich give it an angular appear¬ 
ance. In the true Pipe Fish ( Syngnathus) the mouth is situated at 
the end of a tubular beak. The eggs in some species are hatched in a 
sort of bag, formed by a puffing up of the skin under the abdomen, or 
at the base of the tail, which splits asunder to allow the escape of the 
young. Many of the species are straight, but some contract after death, 
so as to form a grotesque resemblance to a horse in miniature, whence 
they are called Sea Horses {Hippocampi.) The Pegasi {Pegasus) 
differ from them by the mouth being placed at the base of a prominent 
muzzle. The ventral fin of some of the species of this genus is very 
large and expanded, whence their name. 
The tubular-mouthed fishes (FiSTULARiDiE) are so called from the 
