FISHERY BULLETIN VOL 77, NO '.' 



sumieri. This is to be expected because both C. 

 dussurnieri and P. glauca are viviparous forms in 

 which a yolk-sac placenta has been developed. 

 (See Prasad 1944, for a discussion of phylogenetic 

 significance.) 



Metten (1941) observed that the oviducal gland 

 of Scyliorhinus canicula has a function beyond 

 that of albumen and shell production. He found 

 active male spermatozoa in every mature female 

 oviducal gland that he dissected. In S. canicula 

 this gland is a seminal receptacle. Eggs are fer- 

 tilized, not in the anterior oviduct as had been 

 previously suggested, but in the oviducal gland 

 itself It is not known how many species of elas- 

 mobranchs share this trait. Matthews ( 1950) could 

 not find sperm in the oviducal gland of the basking 

 shark. Prasad (1944) observed the presence of 

 spermatozoa in the oviducal glands of four vivip- 

 arous species from the Indian Ocean: Car- 

 charhinus dussurnieri . Hemigaleus balfouri, Sco- 

 liodon palasorrah , and S. sorrakowah. He also 

 gives an excellent account of the search for a "re- 

 ceptaculum seminis" and its existence in other 

 animals. Prasad (1945) observed spermatozoa in 



the oviducal gland of the tiger shark, Galeocerdo 

 cuvieri. 



Stevens ( 1974) found that IG""! of female British 

 blue sharks had tooth cuts. Of these, three were 

 dissected and oviducal glands examined for sper- 

 matozoa. His failure to find spermatozoa could re- 

 sult from technique, sample size, or the dynamics 

 of the British blue shark population which con- 

 tains very few males (Stevens 1974). Only 4''^ of 

 the males in his sample reached sexual maturity 

 as defined by my criteria based on the spermato- 

 phore development of western Atlantic blue 

 sharks. 



I have found spermatozoa in the oviducal glands 

 of 79 of 160 female blue sharks collected over a 

 3-yr period (Figure 25). In all cases sperm was 

 detected in a cross section of the posterior third of 

 the oviducal gland using light microscopy. Fifteen 

 micrometer sections were examined at 120-500 

 diameters magnification and the presence of 

 brightly stained sperm confirmed at 1,250 diame- 

 ters (Figure 26). 



In the last year of field collections, comparative 

 tests were conducted to determine if the presence 



uU 



TlM 



B 



I _ 



I X EGG DIAMETER 



I ^*^ FOR INSEMINATED 

 $'S. N=62 



r-n — \ '""{""V '''\ 1 — I — r^ 



"h ^ r^^ 



100 140 ISO 



BODY LENGTH (cm) 



I I r — I I I 



220 260 



Figure 25, — Frequency of occurrence of female blue sharks off Bay Shore, N.Y.. with data on insemination, egg diameter, and body 

 length relationship: Ai uninseminated females, Bi adult females. Cl insemmated females. 



464 



