SCYLLIUM CANICULA 



247 



muscles, and as the peritoneum covering them is quite thick they are 

 not seen until it has been removed. The kidneys in the two sexes 

 are fairly similar, so that they need not be dealt with separately. 

 The front end of the kidney in the female is very small and, 



B. 



FIG. 81. 



A,, urogenlial system of the female; B., urogenital system of the male dogfish; ab.p., 

 abdominal pores ; cl., cloaca ; cp., claspers of the male ; /., rudiment of the oviducal opening 

 in the male ; M.d., metanephric ducts ; mtn., metanephros ; od., oviduct; ae., cut end of oesopha- 

 gus ; o.g., oviducal gland ; ov., ovary; P./., pelvic fins ; R., rectum; s.s., sperm sacs ; T., testis ; 

 u.p., urinary papilla in the female ; ug.p., urogenital papilla in the male ; M.S., urinary sinus ; 

 v.e., vasa efferentia; v.s., vesicula seminalis; W.D., Wolffian duct; W.G., Wolffian gland or 

 mesonephros. 



although perhaps retaining its excretory function to a certain 

 extent, is so reduced that it may be considered almost vestigial. It 

 presents the appearance of a series of small isolated patches of a 

 brownish colour which increase slightly in size towards the hinder 

 end. The posterior portion of the kidney is much larger, being 

 wider and considerably thicker, and it forms one discrete body 

 partially divided up into lobes. 



