152 



ZOOLOGY 



SECT. 



abd ap 



-thgldl 



opening of the rectum, while in Chiloscyllium they remain distinct 

 and have separate cloacal openings. Each kidney consists of two 

 parts, anterior and posterior. The former (Fig. 773, r. meson.) is 

 a long narrow ribbon of soft reddish sub- 

 stance, which runs along throughout a 

 great part of the length of the body-cavity 

 at the side of the vertebral column, 

 covered by the peritoneum. The posterior 

 portion (r. metan.) is a compact, lobulated, 

 dark-red body, lying at the side of the 

 cloaca, continuous with the anterior por- 

 tion ; like the latter, it is covered over by 

 the peritoneum. Both portions have their 

 ducts. Those of the anterior are narrow 

 tubes, which run over its ventral surface 

 and become dilated behind to form a pair 

 of elongated chambers, the urinary sinuses 

 (Fig. 779, ur. sin), which unite into a 

 median sinus (med. ur. sinus.), opening into 

 the cloaca by a median aperture situated 

 on a papilla, the urinary papilla. The 

 ducts of the posterior portion, the ureters, 

 which are usually from four to six in num- 

 ber, open into the urinary sinuses. 



In the male there are two elongated, 

 soft, lobulated testes, each attached to the 

 wall of the abdominal cavity by a fold of 

 peritoneum the mesorchium. From each 

 testis efferent ducts pass to the anterior 

 end of a long, narrow, strap-shaped body, 

 which corresponds to the anterior portion of 

 the kidney in the female. This is the 

 rpididymis, the duct of which is a convo- 

 luted tube running along the entire length 

 of the mesonephros, and where it leaves 

 the latter posteriorly becoming a wide 

 tube the vas dcferens or spermiduct 

 which opens into a special median com- 

 partment of the cloaca, the urino-gcnital 

 sinus. Posteriorly the spermiduct dilates 

 to form a wide thin-walled sac, the vesi- 

 cula seminalis. Closely applied to the 

 latter is a thin- walled elongated sac, the 



sperm -sac. Anteriorly the sperm-sac narrows to a blind extremity. 

 Posteriorly the right and left sperm-sacs combine to form the 

 urino-genital sinus. The posterior part of the kidney has the 

 same character as in the female ; its ducts, usually five in number 



-clo.afj 



ur.afi 



FIG. V7S. Chiloscyllium. 



Oviducts, abd. ap, common 

 abdominal aperture of ovi- 

 ducts ; do. ap, cloacal aper- 

 ture ; sh. ffld, shell-gland ; 

 ur. ap, urinary papilla. 



