The Embryology of Chlamydoselachus 547 



through Dr. N. Yatsu, he has sent me two photographs showing the body cavity open- 

 ed along the mid-ventral line. The better of the photographs, and the one which he re- 

 produced, is shown herein as Text-figure 3. Momose also kindly sent me his drawing of 

 the abdominal viscera of his Chlamydoselachus with the two huge ovaries sketched in, as 

 seen in Text-figure 9. Each ovary contains five great eggs, measuring 80-83 mm. in di- 

 ameter. It is interesting to find in Momose's photograph (Text-figure 3) and sketch 

 (Text-figure 9) absolute corroboration of what is seen in Dean's 35-year-old photograph, in 

 his rough colored wash drawing, and in his rougher pencil sketch. 



So far as all this evidence goes, it strongly indicates that more eggs ripen in the right 

 than in the left ovary — a total of 25 in the right and 19 in the left ovary in the four cases 

 cited above. In Dean's specimen, having 5 eggs in the left and 11 (in two rows) in the 

 right, and in Momose's fish having 5 eggs in each ovary are found the only cases on record 

 in which the left ovary contained eggs approaching maturity. Smith's 1550-mm. specimen 

 contained young eggs in both ovaries, but the larger ovocytes (up to 17 mm. in diameter) 

 were found in the left ovary. Even with these bilateral ovaries considered, the weight of 

 evidence is that the right ovary is the predominant egg-producer. 



It is interesting to note the relative positions of the ovaries with regard to each other. 

 Carman's drawing (1885) shows the two ovaries on the same level (Text-figure 8 herein). 

 Hawkes (1907) says of her specimens (number not noted) that "The right ovary is placed 

 somewhat more anteriorly than the left". Dean's rough sketch shows the two organs on 

 the same level. Smith's young and sexually immature fish (1398 mm. long) had the two 

 ovaries on the same level (Text-figure 10 herein). Another, measuring 1550 mm. with 

 eggs up to 17 mm. in the left ovary, had this ovary somewhat further forward than the 

 right (Text-figure 11). In each of his two other mature specimens (1350 and 1585 mm. 

 long) the right ovary was placed markedly forward of the left (Text-figures 14 and 15). 

 Momose's sketch shows the relative positions of the ovaries in his specimen. The right 

 ovary is placed forward of the left by about two-thirds the diameter of one of the huge 

 eggs (Text-figure 9). 



Of the eight females for which we have data, three had the ovaries on the same level 

 (one being sexually immature), one had the left anterior to the right, and four had the 

 right placed further forward. This difference in position brings the right ovary nearer to 

 the entrance funnel to the oviducts. 



The matter of the one-sidedness of elasmobranchs in their reproductive organs — 

 particularly that in Chlamydoselachus the right ovary only tends to be functional — is of 

 very great interest and deserves some study. Fortunately I have made some firsthand 

 observations as to unilaterality of the functioning of both ovaries and oviducts in various 

 sharks and rays. It seems best to postpone the consideration of these data for ovaries 

 until the oviducts of Chlamydoselachus have been studied, since in them also a tendency to 

 unilateraHty will be found, and since the functioning of the two are interdependent. But 

 before going into the matter of oviducts, it seems well to consider here the question of the 

 si2;e attained by the egg before it is discharged from the ovary. 



