444 Bashford Dean Memorial Volume 



Among related forms, the female Heptanchus (Daniel, 1934) presents a much more 

 highly differentiated condition of the duct system. Only those collecting tubules from 

 a little more than the anterior halves of the mesonephroi drain into the mesonephric 

 ducts which, at the level of the ovaries, are coiled somewhat like the corresponding 

 portions in the male. This coiling is correlated with the presence of a rudimentary testis. 

 The remaining tubules, which lead from the broad and thick posterior portions of the 

 mesonephroi, open into a pair of very large tubular "ureters" which, in this region, lie 

 dorsal and lateral to the mesonephric ducts. Usually, each ureter joins a mesonephric 

 duct, posteriorly, before the combined vessels enter the single urinary sinus. In an 

 anomalous specimen with two urinary sinuses, right and left respectively, the meso' 

 nephric duct and the ureter of each side open separately into the urinary sinus. 



The convergence and union of collecting tubules from the posterior portions of the 

 mesonephroi, to form "ureters'" which enter the urinary sinus directly, are features 

 more characteristic of the highly differentiated elasmobranchs, especially the skates and 

 rays. Daniel (1934) states that the WolfBan duct (mesonephric duct) decreases in im^ 

 portance as we approach the rays. In the female Squalus suc}{lii (Daniel, 1934, p. 295 

 and Fig. 253a) the condition is essentially the same as in Chlamydoselachus : the mesone- 

 phric duct receives the collecting tubules from practically the whole of the mesonephros. 

 This is probably the primitive condition. It seems extraordinary that Heptanchus, in 

 many respects one of the most primitive of living sharks, should have departed so far 

 from this archaic type of duct system. 



GENITAL ORGANS OF THE FEMALE 



From an inspection of Text-figures 85 to 88, it will be seen that my four specimens 

 display various degrees of development of the genital organs. Some of these differences 

 are certainly associated with age, others may possibly be concerned with a sexual cycle. 

 Though specimen No. IV is almost as large as the largest, its reproductive system retains 

 strict bilateral symmetry, and is obviously immature. In all the other specimens the 

 reproductive organs are better developed on the right side save that in No. Ill, which is 

 probably not quite mature, the left ovary shows a slightly more advanced stage of de- 

 velopment than the right. Specimens I and II are fully mature. Some structures seem 

 better developed in No. II than in No. I, but since it is probable that there is a definite 

 breeding season (Gudger and Smith, 1933, p. 302) these differences may be correlated 

 with a sexual cycle. 



The largest known female, collected in Japan by Dr. Bashford Dean, had a total 

 length of 1960 mm. The average length for 35 females, comprising all known post-natal 

 female specimens for which the length has been recorded, is 1532 mm. (Gudger and Smith, 

 1933, Table V, p. 263). We do not know how many of these were sexually mature, but 

 only two of them had a length of less than 1220 mm. My two fully mature female 

 specimens, Nos. I and II, measure 1350 mm. and 1485 mm. respectively. My largest 

 specimen, No. Ill, has a total length of 1550 mm., yet it seems not quite mature. My 



