416 THE ZOOLOGIST. 





The law of the production of ova may be expressed as 

 follows : — The numbers of eggs produced by female Lobsters 

 at each reproductive period vary in a geometrical series, while 

 the lengths of the Lobsters producing these eggs vary in arith- 

 metical series. According to this law we have the following : — 



Series of lengths (in inches) 8 10 12 14 16 



Series of eggs 5,000 10,000 20,000 40,000 80,000 



An examination of nearly a thousand cases shows that this 

 law usually holds good. 



The question of fertilization of the egg is a very difficult one, 

 and nothing is yet known of how the spermatozoon is conveyed 

 to the egg, and penetrates its membranes. We know, however, 

 that copulation takes place in the spring and summer months, 

 and probably at other times of the year; that fertilization is 

 effected outside the body ; that the semen is stored in a peculiar 

 pouch or receptacle, where it may retain its vitality for months, 

 at least. 



The eggs are carried, attached to the body of the female for 

 a period of from ten to eleven months, that is, on the coast of 

 Massachusetts, from the middle of July or the 1st of August to 

 the middle of the following June. The period of fosterage 

 undoubtedly varies considerably in eggs not produced in summer, 

 some of which may hatch in the fall and possibly in the winter 

 months. 



Some Lobsters become sexually mature when they are eight 

 inches long, while a relatively small number do not produce eggs 

 until they have attained a length of twelve inches. The majority 

 are mature when 10^ inches long. 



The law of survival of the larvae I have discussed in a paper 

 already referred to (' Bulletin of the U.S. Fish Commission,' 

 vol. xiii. 1893). It is probable that the survival of two out of 

 every ten thousand larvae hatched is a high estimate, since the 

 female of average size produces upwards of ten thousand eggs at 

 a single laying, and may have the opportunity of reproducing 

 more than once in the course of her life. The number of 

 survivals must be less than the number of adults caught and 

 destroyed each year, since the fishery is declining, and in some 

 places has been destroyed through the persistence with which it 

 is carried on. 



Shortly after hatching her brood, the mother Lobster moults, 



