458 ZOOLOGY. 
ton; a single opercular bone, while the snout and lower 
jaw are prolonged into a tube, with the mouth at the 
end. The chief peculiarity, however, is the gills, which are 
developed in the form of a row of tufted lobes on each side 
of the branchial arches. The scales are large, forming an- 
gular plates arranged in longitudinal rows (Gill). In Sole- 
nostoma of the Indian Ocean the female carries the eggs in 
a pouch formed by the union of the ventral fins with the 
integument of the breast. 
The male of the pipe-fish (Syngnathus peckianus Storer) 
receives from the female the eggs, and carries them in a 
small pouch under 
his tail, which is 
open beneath 
through its whole 
length. This sin- 
gular mode of mas- 
culine gestation is 
still farther per- 
fected in the sea- 
horse (Hippocam- 
pus hudsonius De 
Kay, Fig. 416), 
which lives off- 
shore from Cape 
Cod to Cape Hat- 
teras). The pouch 
is situated on the 
breast. The male, by simple mechanical pressure of its 
tail, or by rubbing against some fixed object, as a shell, 
forces the fry, to the number of about a thousand, out of its 
brood-pouch, the young at this time measuring about twelve 
millimetres (5-6 lines) in length. In the young the head is 
at first rounded, the snout being short and blunt (Lockwood). 
Order 8. Plectognathi.—This group, represented by a few 
singular forms, such as the trunk-fish, file-fish, puffers, and 
sun-fish, is characterized by the union of the bones of the 
upper and especially the lower jaws. There are few verte- 
bre, the scales are often modified to form spines, and the 
Fig. 416.—Sea-horse, mule. with the young issuing 
from the brood-pouch.—After Lockwood. 
