CHONDROPTERYGII. 635 



In common with their congeners, these fish, unlike most of 

 the class, have a personal intercourse between the sexes, 

 which takes place at the beginning of the hot season, accord- 

 ing to the latitude where they may be at the time, and not 

 very far from shore. The eggs in considerable numbers are 

 hatched in the mother, but not all at the same time, part 

 toward the end of summer, when a parturition takes place of 

 three or four, and so from time to time, till about thirty are 

 produced. It appears that a shark of about ten feet long 

 contains about forty eggs or young. At its birth the young 

 shark is about seven or eight inches long, and it is quite 

 unknown how long they are in attaining their full size, or 

 what is the usual period of their life. 



The principal enemies of this formidable fish appear to be 

 the cetacea, especially the cachalot, with whom however the 

 shark engages in sometimes long and dubious combat. They 

 are also tormented by a vast number of intestinal worms. 



The Carcharias, (Squalus VulpesJ the Thresher or Fox 

 Shark, frequents our coasts, and is a very large species, being 

 sometimes found fifteen feet long. It is called the fox from 

 the length and roughness of its tail, and according to Borlase 

 is called the thresher from its habit of defending itself by 

 blows of' the tail. It is an inhabitant of the Mediterranean 

 as well as of the ocean. 



From Col. Hamilton Smith, we have received the following 

 communications, respecting these fishes. 



Sharks are said to be innocuous in certain estuaries on the 

 Western Coast of Africa, where no dead bodies are allowed 

 to be thrown into the water, while in others, they are so 

 voracious as to leap out of the sea to catch their prey. The 

 colonel himself has seen sharks so eager as to run ashore 

 and struggle in the surf until they were washed back again, 

 or knocked upon the head. 



When Colonel Smith was in Jamaica, the Captain of a 



