22 



3- Observations at the Marine Laboratory at St. James 

 TO Determine the Breeding Habits, Etc., of the 

 Crawfish. 



About the beginning of October, 1906, four females were 

 procured from vSaldanha Bay and placed in the tanks of the 

 Marine Station at St. James. They were obtained in the 

 course of an enquiry to determine the smallest size of mature 

 females carrying eggs with a view to the fixing of a size limit. 

 After about two hours' fishing, the fishermen, who knew at 

 once in what locality females in berry could be caught at 

 that time, were able to procure ample material in the form 

 of a full boat-load, all females in berry. There were about 

 600 in all and were from near the mouth of the Bay. Four 

 of the smallest of these were selected, all being about the 

 same size, namel}^ 3^^ inches in length of carapace. These may 

 be designated A, B, etc., and there subsequent history w^as as 

 follows : — 



Female A. — On the 15th October, igo6, the eggs hatched 

 out and produced numerous larvae. On the 28th April of the 

 following year (1907) the crawfish cast its shell, and again on 

 the 4th July of the same year. About the i8th and 19th it 

 was attended by two males, which had been placed in the tank, 

 and on the 20th it was observed to be carrying a full mass 

 of eggs below the tail, copulation and the extrusion of eggs, 

 as in nearly all other cases, having taken place during the 

 night. The two males about this time were very pugnacious, 

 the larger driving off the smaller. After the extrusion of the 

 eggs, the larger male returned to his customary place in the 

 tank, though keeping a watchful eye on the other male. At 

 times he resumed his attacks on his ri\'al, dri\'ing him off to 

 remote corners of the tank, and even then occasionally renew- 

 ing his hostilities. It was not until, by accident or superior 

 intelligence, the smaller male was able to reach a stone sus- 

 pended in the tank that he was left in peace, the larger male, 

 in spite of repeated attempts to reach him, being unable to 

 do so. Thereafter the larger male was left in undisputed 

 possession of the females. It would appear, therefore, that 

 the animal is polygamous in its habits, a fact of importance 

 in restrictive measures which may be adopted to regulate 

 the industry. 



The eggs were shed about the 5th October, 1907. On the 

 29th of May of the following year (1908) the shell w^as again 

 cast, and on the 6th July the crawfish was again carrying 

 eggs externally ; these were shed on tlic i8th of September. 



