ORDER Il. CHONDROPTERYGI. (FIXED GILLS.) 213 | 
pounds. They are readily caught with the hook. These shoals seldom 
remain in shallow water, or near the shore, more than three or four days ; 
they feed upon the offal and garbage thrown upon the bottoms by the fish- 
ermen, and so perfectly do they clean the ground, that it is observed by old 
fishermen, that when the spring shoal of Dog-fish has been unusually large, 
the cod-fish are found in much larger numbers upon the same localities 
afterwards. In Scotland, the flesh of this fish is much eaten by the lower 
classes, and the refuse portions afford a valuable manure.” 
ZyGENA.—In this genus is found that singular-looking fish, the /Zan- 
mer-headed Shark. The snout of this fish is singularly produced, forming 
two picces, like a double-headed hammer, with an eye in the middle of each 
extremity. Some of the species attain a very large size. 
Noripamus. — In this genus are found the largest specimens of the Shark 
family. They have six gill-openings, triangular teeth above, and like a saw 
below. Some species, among them the Squalus maximus, are between 
thirty and forty feet in length. They are harmless fishes. . 
A remarkable specimen was exhibited in Boston in 1868, under the sen- 
sational name of Sea Serpent. It was thirty feet long, and had all the 
characteristics of a shark, but in addition a pair of legs, which appeared to 
grow forward from the base of the ventral fins. Those who had it in 
charge asserted that it made frequent excursions upon the land, and was 
shot in a meadow between two ponds. I was not, however, able to extract 
from them anything reliable, and have found it utterly impracticable to 
obtain an authentic history of this really curious animal. 
Pristis. —The Saw-fishes. They have a long body, like the sharks, 
with the gill-openings below ; the snout extended like the blade of a sword, 
and with strong, trenchant teeth on both edges, which give it the appearance 
of a saw, whence the popular name of the fish. This singular weapon is 
probably a provision of nature for the defence of the animal against the 
attacks of more powerful foes. Iam obliged to destroy another “romance 
b 
of the sea” in which the Saw-fish figures as engaging in frightful duels with 
the gigantic Mysticetus, or uniting with the Sword-fish and Grampus in 
making war on that mighty denizen of the ocean ; the Saw-fish is a shore fish, 
and does not frequent the deep waters which the larger whales inhabit, and 
we must, therefore, consider such battles as inventions of the novel writers. 
Rata. — The Rays. These singularly unsightly fishes resemble the 
side-swimmers by the flatness of their form, but differ widely from them in 
many other particulars. Like the sharks and sturgeons, they are cartilagi- 
nous fishes, and as their branchi adhere to the cells, these respiratory mem- 
branes are not furnished with gill-covers, but communicate freely with the 
NO. XVI. 80 
