THE DOG-FISHES. 



33 



the most part on Crabs and Lobsters, though they readily take any tempting food that conies in 

 their way. They rarely come near into shore, and are caught in summer and autumn. The eggs 

 of these fishes are contained in oblong purse-like cases, as tough as leather, with long tendrils at 

 the four corners, which coil up and hold the egg to some coralline, or gorgonia, or sea-weed. 

 The eggs are deposited one or two at a time. The Nurse Hound deposits them late in the 

 year, but the Rough Hound lays its eggs throughout summer and 

 autumn. Its purses are of a pale yellow colour, with tendrils which 

 may be stretched out to a length of two feet. The eggs have been 

 found unhatched as late as the middle of December. There are four 

 slits at the corners of the egg-case, but their function has not been dis- 

 covered. The flesh of the Nurse Hound is too rank to be eaten, but 

 in the west of Cornwall the Rough Hound is made into Sea-dog soup, 

 called from its ancient British name " Morghi," but in the Mediter- 

 ranean the Rough Hound appears to be an ordinary item of food. 

 Sharks are of rapid growth, and reach their full size in a few years, but 

 there are no means of judging what age they attain. The Nurse 

 Hound grows to a length of four or five feet. Its colour is dusky-red, 

 with many large dark spots on the body and fins. The skin is rough 

 with minute spines, which are directed backwards. The body is 

 elongated posteriorly; the pectoral fins are placed low down at the 

 sides of the head, and are wide. There are five small branchial clefts 

 placed close together in front of the pectoral fin. The mouth is very 

 close to the end of the snout, and when opened is circular. The Black- 

 mouthed Dog-fish, which forms the genus Pristiurus, differs in having 



a long snout with the mouth placed below the large eye. It is well known in Italy, where it 

 has received from the Italian fishermen the name " Bocca d'Inferno," or " Mouth of Hell." The eggs 

 are deposited in cases which have, according to Yarrell, the tendrils at one end only, and too short to 

 be capable of twining round any fixed substance. The purses are about an inch and a half long, of a 

 tawny yellow-brown colour, with a smooth shining surface. The body is spotted, but the spots are 

 oblong and arranged in two rows. The colour of the upper part is made up of many tints of brown 

 and yellow, while the belly is pale. The dorsal fins are placed far back, the first dorsal beginning 

 behind the ventral fins. These fishes are a little over two feet long. 



The Dog fishes are widely distributed, some of the species rang- 

 ing over the Indian Ocean, others from Japan to Amboyna ; one is 

 recorded from Tasmania, another from Chili, and one or two from 

 the Cape. There are in this family five other genera, which have 

 much the same distribution as the genus Scyllium. 



EGG PURSE 



NURSE HOVND. 



B 



EGG OF CESTRACION (A) ; SECTION" 

 OF THE SAME (B). 



FAMILY VI. CESTRACIONTID^E. 



This family is known only from the genus Cestracion, of which 

 there are four species. Here, for the first time, spines are met 

 with in front of both the dorsal fins ; the nostrils unite with the 

 cavity of the mouth, which is narrow, and has the upper lip 

 divided into seven lobes. The teeth in both jaws are similar ; 

 they change their character as the animal grows older. In the 



middle there are small teeth, which at first have from three to five cusps, but afterwards become 

 small and blunt. External to these are lai'ge lateral teeth, twice as broad as long, which are arranged 

 in oblique series so as to form a sort of tesselated crushing surface. The best known species is the Port 

 Jackson Shark (Cestracion p/tilippi), which ranges from Japan to New Zealand The backbone con- 

 tains a hundred and ten vertebrae, only fourteen of which intervene between the skull and the first 

 dorsal spine. The body is marked with more or less distinct dark bands, which give the fish a Zebra- 

 like appearance. There is a second Australian species, one from the Galapagos Islands, and another 

 195 



