The Embryology of Chlamydoselachus 535 



In the handwriting of Dean's unnamed Japanese collector — possibly Kuma — are two 

 records. In the ovary of a 1500'mm. Chlamydoselachus taken February 8, 1905, six 

 "immature" eggs were found. And on April 30, 1903, he found in a female, 1670 mm. in 

 length, three ''immature" eggs in one ovary and nine in the other. Unfortunately the 

 si2;es of these eggs were not noted. However, under date of April 27 (1902?), Dean 

 diagrammatically figured and also photographed the ovaries with eleven large eggs in 

 a female measuring I960 mm. — the largest Chlamydoselachus on record. In the left ovary 

 were five eggs, size 70 x 30 mm., and in the right nine of the same size and two measuring 

 60 X 30 mm. As will be seen later, these eggs, though large, were not mature, but one 

 may conjecture that they would have reached maturity later in the calendar year. Thus 

 Dean recorded on October 1, 1905, ''female, no eggs [in oviducts ?], large ovar." 



Since the above was written, Momose (1938) has described the visceral anatomy of 

 a nearly ripe female taken in Sagami Bay, November 28, 1938. Each ovary contained five 

 eggs measuring from 80 to 83 mm. in diameter. Momose has kindly sent me two photo- 

 graphs showing this fish opened along the mid'ventral line to reveal the ovaries. The 

 better of these photographs is reproduced herein asText'figure 3. Since ripe ovarian eggs 

 and newly fertilized eggs (Figures 1, and 4, plate I) average about 95 mm. in diameter, it 

 is clear that these 80-83'mm. eggs were almost mature. 



The evidence from the ovaries is scanty but nevertheless significant. To recapitulate, 

 ovarian eggs taken February 8 and April 30 were noted as "immature" but no sizes were 

 recorded. However, on April 27 some eggs were measured and found to be 70 x 30 mm. 

 On October 1 a "large ovar." was noted, and on November 28, several eggs measuring 

 about 83 X 80 mm. were photographed (Text'figure 3) — eggs almost "ripe". These data 

 indicate strongly that eggs in the ovaries of Chlamydoselachus ripen at any season through- 

 out the year. But better evidence of a long breeding season will now be introduced. 



STAGES OF EMBRYOS IN THE UTERI 



The evidence as to the surprising range of the breeding season of the frilled shark, 

 based on the ages of embryos obtained from the uteri, at various times in the year, will 

 now be set out in chronological order. 



Nishikawa (1898) gives the first intimation of a definite breeding season for the frilled 

 shark. He states that "... the breeding season is spring, extending from about the end of 

 March to the beginning of June". He had eggs in early and late blastula stages but he 

 does not give the dates when these were obtained. Of his seven gravid female fish, 

 he gives date of collection for but one. His youngest batch of embryos (from a 1700-mm. 

 female) came to him on May 26, 1896. These embryos were six in number and measured 

 32, 35, 43, 48, 50 and 60 mm. long respectively. 



Dean's notes give a far greater range of dates when uterine eggs and embryos were 

 collected, and ordinarily he gives measurements for one or both. Thus he notes "1905, 

 Early Jan. [not JuneY^ eggs with embryos 11.5, 15.5, and 20 mm." Furthermore, in the 

 jar of material from Columbia University referred to above there are two embryos of 



