xiii PHYLUM CHORD ATA 159 



the right of the middle line of the abdominal cavity, attached by a 

 fold of peritoneum, the mesoarium. On its surface are rounded 

 elevations or follicles of various sizes, each containing an ovum 

 of a bright yellow colour. There are two oviducts (Miillerian 

 ducts) entirely unconnected with the ovaries. Each oviduct 

 (Figs. 827 and 835, ovd.) is a greatly elongated tube extending 

 throughout the entire length of the abdominal cavity. In front 

 the two unite behind the pericardium to open into the abdominal 

 cavity by a wide median aperture (ovd'.). At about the point of 

 junction of the middle and anterior thirds is a swelling marking the 

 position of the shell-gland (sh. gl.}. The posterior part dilates to 

 form a wide uterine chamber, and in Scyllium the two unite to 

 open into the cloaca by a common aperture situated just behind the 

 opening of the rectum, while in Hemiscyllium they remain distinct 

 and have separate cloacal openings. Each kidney consists of two 

 parts, anterior and posterior. The former (Fig. 827, r. meson, 

 Fig. 835, k') is a long narrow ribbon of soft reddish substance, 

 which runs along throughout a great part of the body-cavity at 

 the side of the vertebral column, covered by the peritoneum. The 

 posterior portion (r. metan, k) is a compact, lobulated, dark-red 

 body, lying at the side of the cloaca, continuous with the anterior 

 portion ; 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. 836, 

 ur. sin.), uniting behind into a median sinus (med. ur. sin.), 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 number, open into the urinary 

 sinuses. 



In the male (Fig. 835, A) 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 anteriorly, a small 

 number of efferent ducts (ef.d) pass to the anterior end of a long, 

 narrow, strap-shaped body, which corresponds to the vestigial 

 anterior portion of the kidney in the female. This is the epididymis ; 

 the duct, spermiduct or vas deferens, runs along the entire length of 

 the non-renal part of the kidney, or " Ley dig's gland" and, where 

 it leaves the latter posteriorly, becomes a wide tube, which opens 

 into the urinogenital sinus (u. g. s.), a median chamber projecting 

 into the cloaca. Posteriorly the spermiduct dilates to form a wide 

 thin-walled sac, the vesicula 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 urinogenital sinus. The 

 posterior part of the kidney has the same character as in the 

 female ; its ducts, usually five in number on each side, open into 



