32 



NATURAL HISTORY. 



and are directed towards the angles of the month. In front, in the middle line, are four more awl- 

 shaped teeth. The six openings for the gills are placed very close together, and extend under 

 the throat so as almost to encircle its lower part. The scales are very short and leaf-shaped, with a 

 median keel which runs to the sharp point. Specimens taken off Yentnor have measured eleven or 

 twelve feet in length. The pectoral fins are unusually wide and triangular. The caudal fin is about a 

 quarter of the length of the fish, and more slender than in any other British Shark except the 

 Thresher. The hinder two-thirds of the upper margin of the tail are armed with three parallel rows 

 of spines, the lateral rows diverging outward. Though known as the Grey Shark, the back and 

 tins have a blackish-brown colour, but it is white underneath, and of a warm grey tint at the 

 sides. It has several times been taken with a line on the South coast of Britain. Large speci- 

 mens are said to have many rows of teeth in the lower jaw. It is often met with in the Medi- 

 terranean, and frequents the Atlantic. The three other Sharks closely allied to this, which have 

 been placed in the section Heptanchus, are Notidanus platycephalus, distinguished by its short 

 blunt snout, which is found only in the Mediterranean; and the Notidanus cinereus, found in 

 the Mediterranean and adjacent coasts of the Atlantic, which has the snout prolonged and pointed. 

 The third seven-gilled Shark, called Notidanus indicus, ranges from the Cape of Good Hope to 

 California. 



FAMILY V. THE SCYLLIID.E, OK DOG-FISHES. 



The term "Dog-fish," as might be expected, is used vaguely by fishermen for a number of 

 distinct Sharks. Along the English coasts there are several nearly-allied forms known as the Spotted 

 Dog-fish, or Nurse Hound, and the Black-mouthed Dog. The Nurse Hound, or larger Spotted Dog 

 (Scyllium stellare), and the smaller species known as the Rough Hound, or lesser Spotted Dog (Scyl- 

 lium canicula), usually live at the bottom of the sea, and in rough and rocky places. They feed for 



NURSE HOUND. 



