212 DIVISION I. VERTEBRAL ANIMALS.—CLASS IV. PISCES. 
ful blows it deals with its tail when attacked. It often visits our waters, 
and feeds on mackerel and menhaden. 
Lamna.— ‘his genus has the point of the nose conical, the nostrils 
pierced on its under surface, and the five gill-openings before the pectorals. 
L. Punctata. —The Mackerel Shark. This is the most common shark 
of the Atlantic, and abounds on the American coasts, where it exercises its 
mischievous propensities among the lines of the fishermen, often biting them 
@ them of their prey. Its length is from six to ten feet, 
fo. 
off, and thus robbin 
and its weight from three to four hundred pounds. Like the other sharks, 
it appears to have little sensibility, and is very tenacious of life; I have seen 
one of these fishes eat its own liver, which protruded through a wound made 
by a harpoon, 
Spivax. —'Two dorsal fins, with a strong spine at the anterior edge of 
each ; absence of the anal fin; teeth in several rows, small and cutting, dis- 
tinguish this genus. 
S. Anthias. —The Dog-fish. This isa common species well known to 
our fishermen, and resembles the shark, both in appearance and in its say- 
age temper. The English call it the Piked Dog-fish, from the spines of 
the dorsal fins. The length is from two to three feet ; the body is slender. 
Dr. Storer furnishes the following description : 
“All the upper part of the body of a slate-color, which is deeper upon 
the head; lighter below the lateral line; beneath, white; just under the 
lateral line, a row of circular white spots; a few similar spots irregularly 
distributed upon the back. Length of the head to the whole length of the 
fish, nearly as four to nine; the head flattened above, tapering to a blunted 
snout. Eyes horizontally elongated; their longest diameter nearly equal 
to one fourth the length of the head; pupils small, black; irides silvery, 
with a cupreous tint. Orbit large, allowing great motion to the eye. The 
distance between the eyes equal to more than half the length of the head. 
Between the eyes, two longitudinal patches of numerous mucous glands, 
which are indistinctly continued nearly to the extremity of the snout. Tem- 
poral orifices back of the eye, and just above the line of the eye; their 
length is equal to the short diameter of the eye. All the lower portion of 
the head, in front of the mouth, sprinkled over with mucous orifices. 
“In the spring and autumn, the Dog-fish appear in shoals in our bay ; 
they are frequently met with in immense numbers. At their appearance, 
smacks are fitted out at Truro and Provincetown for their capture, to the 
neglect of other fishing, for the oil they furnish ; and it is said to be quite a 
valuable business. The fishes themselves are dried for food for the cattle, 
and their skin is considerably used for polishing by the mechanic. They 
average about eight or ten pounds weight; sometimes they weigh fifteen 
