G. GENERAL NATURAL HISTORY AND ZOOLOGY. 351 



o-regation of so large a number of detached scales would be 

 a problem extremely difficult of solution. Perfectly authentic 

 instances are on record of small fish, shells, etc., being taken 

 up in storms and scattered over the earth; but when it comes 

 to special portions of fishes which weigh from five to fifty 

 pounds each, the draft upon one's faith is rather too severe. 



HABITS OF THE CKAW-FISH. 



One of the more novel applications of the general science 

 of pisciculture is to the breeding and rearing of craw-fish, 

 which, in Europe especially, constitute a much-sought-for 

 delicacy, and in the United States are becoming quite fashion- 

 able as an article of luxury. A preliminary to a successful 

 treatment of these animals for commercial purposes must 

 necessarily consist in a careful inquiry into their natural his- 

 tory. This has recently been done, in the laboratory of Pro- 

 fessor Coste, in Paris, by Chantran, who has lately published 

 an interesting memoir on the subject. According to this 

 writer, copulation between the sexes occurs during the win- 

 ter, especially in November, December, and January, and the 

 fertilization takes place on the exterior of the body of the fe- 

 male, which lays her eggs from two to forty-five days after 

 the meeting of the sexes, according to the degree of the ma- 

 turity of the eggs. At the critical moment the abdominal 

 appendices of tiie female secrete a viscous mucus for several 

 hours, after which she throv/s herself upon her back, and curls 

 her tail toward the mouth of the oviduct, so as to form a kind 

 of basin, in which the eggs are received one by one as they 

 are expelled from the ovaries. The eggs then become adher- 

 ent to the mucus just referred to, which is found to be pene- 

 trated by the spermatozoa, which soon make their entrance. 



The incubation of these eggs usually lasts six months, and 

 the young moult ten days after leaving the shell. Their food 

 at this time consists of eg^cj-shells and the shed skin, while 

 the stronger of the young devour the weaker. Other moults 

 take place in succession from twenty to twenty-five days 

 apart, so that the shell is renewed at least five times in the 

 space of eighty days, usually falling in the months of July, 

 August, and September. From this period until the April 

 folio win o- there is no other moult'. The skin is asjain shed 

 successively once a month, in May, June, and July, making 



