32 BROOKLYN MUSEUM SCIENCE BULLETIN 3. I. 
The spilled dogfish is common off the ocean side of Long Island from 
October to June. It is abundant on the North Atlantic coast of Europe 
as well as America, migrating southward in winter, its range extending 
into the Tro]:»ics. During ])art of the year it inhabits deej^er water than 
most of the sharks included within the scope of this ]iaper, but at the 
times of its migrations it ap])ears inshore and at the surface in huge, 
voracious schools, tremendously destructive to other fishes. These form 
the greater part of its food, though it also eats squid, jellxfish, etc. 
Ihifortunate is the fisherman who gets into the schools of " thorndogs." 
If they do not crowd the good fish from that part of the ocean, they eat 
them off his line before he can get them to the surface, or fill and choke 
his nets, which they snarl and cut badly. Twenty thousand spined 
dogfish have been taken in a single haul of a seine off the British coast. 
This species is the "cod shark" of New Jersey- fishermen. On 
Long Island it is sometimes called the bonefish, from its spines. It is 
pestiferously abundant off the mouth of the vSound during the porgy 
season in May. 
We have found s])ined dogfish numerous in late November near the 
bottom at the edge of the continental shelf off New York. Unlike .some 
other fishes, they .seemed little incommoded by the change in ])ressure in 
being brought from deeji water to the surface, and when thrown over- 
board they .started to swim downward again. At this season many of 
them contain well-developed young, three such being the number 
commonly obser\-ed. We have also a record of a female taken near 
Gardiner's Island on June 12, 191 1, which gave birth to .several young on 
the deck of a boat. Couch, in his ' Fishes of the British Islands ' ( 1867 ), 
gives .some interesting data regarding this species. He .says that for nine 
or ten months of the year the female i^roduces young continuously, and 
that the dogfish is somewhat preyed upon by other larger fi.shes. He 
also describes how the fish u.ses the s])ines on its back for defen.se, and 
.states that if a finger be placed on its head, it will bend it.self into a bow 
and .strike .so accurately with the posterior spine that it will prick the 
finger without i)iercing its own .skin. 
From \ear to \ear this si)ecies varies greatl>- in its abundance in 
certain waters, .sometimes being entirely ab.sent. The fact that it is rarely 
utilized for food seems to be due almo.st eiitirel\- to ])rejudice. Formerly 
it was u.sed exten.siveh' in the manufacture of fertilizer or " fish guano." 
On treeless shores, such as Ca])e Cod, dried dogfish frequently .serve as 
fuel. A liver-oil indu.stry was at one time carried on along the New 
