The Anatomy of Chlamydoselachus 431 



THE UROGENITAL SYSTEM 



In Chlamydoselachus, as in other vertebrates, the urogenital system comprises two 

 functionally distinct parts, the excretory system and the reproductive system; but these 

 are so closely related developmentally and anatomically, especially in the male, that it 

 is often convenient to refer to them collectively. 



UROGENITAL SYSTEM OF THE FEMALE 



Since the literature on the urogenital system of Chlamydoselachus is very meager, 

 the following account is based mainly on my own observations and drawings which were 

 made from four large specimens: Nos. I, II and III collected in Japan by Dr. Bashford 

 Dean and now in the American Museum of Natural History, and another specimen 

 (No. IV) kindly lent by Dr. E. Grace White. All four specimens are females. References 

 to the work of other investigators are made throughout the text. Brohmer's (1908) 

 account of the excretory system of an embryo of Chlamydoselachus deals with an early 

 stage and need not be considered here. 



UROGENITAL SINUS IN THE FEMALE 



In some elasmobranchs the expression"urogenital sinus" is hardly applicable to the 

 female, but in the case of Chlamydoselachus I can see no reason for avoiding the use of this 

 convenient term. In all my specimens the urogenital portion of the cloaca is quite plainly 

 marked off from the rectal portion, though the distinction is most clear-cut in the decidedly 

 immature specimen. 



In this specimen (No. IV) a small aperture (Text-figure 85, ug.s.), situated on the 

 dorsal surface of the rectal portion of the cloaca, leads into the urogenital sinus which 

 extends in an anterodorsal direction for a distance of about 13 mm. The urogenital sinus 

 must be examined by dissection. It is about 10 mm. wide, but its opening into the rectal 

 portion of the cloaca has a width of only 5 mm. On each side of the sinus, near its anterior 

 end, there is an opening from the uterine portion of an oviduct. The urinary papilla is 

 a longitudinal fluted ridge, free at its posterior end, situated on the dorsal surface of the 

 sinus a little to the left of the median line. The urethral aperture, a narrow slit not more 

 than 3 mm. long, is located near the center of the papilla. No urethral orifice could be 

 found on the right side of this specimen. 



In specimen No. Ill, which is nearly mature, the urogenital sinus (shown without 

 a label in Text-figure 86) is still sharply marked off from the rectal portion of the cloaca, 

 though its opening is much larger than in specimen No. IV. The orifices of the uteri 

 are not shown in the figure since they open into the anterior portion of the urogenital 

 sinus, which lies dorsal to the rectal cloaca. The opening of the right uterus is large 

 enough to admit a finger; the left is much smaller. The urinary papilla is a broad ridge, 

 not well defined, on the dorsal surface of the urogenital sinus. The single urethral 

 orifice is a round pore (ur.p.), readily admitting a probe. It is situated near the center 

 of the dorsal surface of the urogenital sinus, but a trifle to the left. 



