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Bashford Dean Memorial Volume 



it tapers gradually both anteriorly and posteriorly. Anteriorly, the right urinary sinus 

 is continuous with the right mesonephric duct which was easily probed. 



In Specimen No. II the urinary sinuses (Text-figure 91c) are well developed and are 

 situated close to the median plane. As in the other specimens, they are not united to 

 form a single functional bladder. Each urinary sinus connects posteriorly with a short 

 urethral pore, through which it may be probed. The two uteri are united by their medial 

 walls for a distance of 50 mm. in front of the urogenital sinus, and so have a common 

 dorsal mesentery. The relations of the urinary sinuses to the urogenital sinus and to the 



Text-figure 92. 



Longitudinal section through cloaca and right oviduct of Chlamydoselachus, 



three-fourths natural size. The dorsal side is uppermost. 



ab-p, abdominal pore; cl, cloaca; int, intestine; ov, oviduct; p, caecal pouch, or rectal gland; ua, 



urethral aperture. 

 After Garman, 1885.2, Fig. 2, pi. XIX. 



dorsal mesentery are much the same as in specimen No. III. The left urinary sinus is 

 only 50 mm. long, but it is comparatively broad, having a maximum width of 10 mm. 

 The left mesonephric duct could not be probed. The right urinary sinus is about 100 

 mm. long. It has a maximum width of 7 mm., but there is an abrupt constriction in its 

 posterior third. In its anterior half it tapers very gradually to become continuous with 

 the right mesonephric duct, which was probed for a distance of 20 mm. in front of the 

 urinary sinus. 



In the well-developed urinary sinuses of specimens III, I, and II, the direction of 

 greatest width is determined by the relations to the urogenital sinus and to the dorsal 

 mesentery. In most cases by far the greater portion of the urinary sinus is imbedded in 

 the dorsal mesentery, and the direction of greatest width of the sinus is therefore mainly 

 dorsoventral. In Text-figure 91 some liberties have been taken with the anatomical 

 relations in order to show the full width of the urinary sinuses. 



