The True Sharks 



547 



fishes. They are, however, nowhere very common. The teeth 

 of Dalatias major exist in Miocene rocks. In the genus 

 Somniosus the species are of very much greater size, Somniosus 

 microcephalus attaining the length of about twenty-five feet. 

 This species, known as the sleeper-shark or Greenland shark, 

 lives in all cold seas and is an especial enemy of the whale, from 

 which it bites large masses of flesh with a ferocity hardly to be 

 expected from its clumsy appearance. From its habit of feeding 

 on fish-oft'al, it is known in New England as "gurry-shark." Its 

 small quadrate teeth are very much like those of the dogfish, 

 their tips so turned aside as to form a cutting edge. The species 

 is stout in form and sluggish in movement. It is taken for 

 its liver in the north Atlantic on both coasts in Puget Sound 

 and Bering Sea, and I have seen it in the markets of Tokyo. In 

 Alaska it abounds about the salmon canneries feeding on the 

 refuse. 



Family Echinorhinidae. — The bramble-sharks, Echinorhimdcc , 

 differ in the posterior insertion of the very small dorsal fins, 

 and in the presence of scattered round tubercles, like the thorns 

 of a bramble instead of shagreen. The single species, Echinorhi- 

 niis spinosiis reaches a large size. It is rather 

 scarce on the coasts of Europe, and was once 

 taken on Cape Cod. The teeth of an extinct 

 species, Echinorhinns richardi, are found in the 

 Pliocene. 



Suborder Rhinae. — The suborder Rhino; in- 

 cludes those sharks having the vertebrae tecto- 

 spondylous, that is, with two or more series of 

 calcified lamella;, as on the rays. They are 

 transitional forms, as near the rays as the 

 sharks, although having the gill-openings rather 

 lateral than inferior, the great pectoral fins 

 being separated by a notch from the head. 



The principal family is that of the angel- 

 fishes, or monkfishes {Squatinida:). In this 

 group the body is depressed and flat like that 

 of a ray. The greatly enlarged pectorals form 

 a sort of shoulder in front alongside of the 

 gill-openings, which has suggested the bend of the angel's wing 



Fig. .340.— Brain of 

 Monkfish, Squatina 

 aqualina L. (After 

 Dumeril.) 



