URIXOGEXITAL ORGANS. 141 



coelic body-cavity) in which the movements of the eye occur. 

 There is a renal-portal system furnished by the caudal vein which 

 branches when it reaches the kidney, and the posterior cardinals 

 arise in the kidney. 



The kidney (Fig. 81) of each side is a single gland but by the 

 arrangement of the collecting tubules may be divided into an 

 anterior thin part, the mesonephros (almost absent in the adult 

 female), and a posterior thick well -developed portion the meta- 

 nephros. The longitudinal duct extends along the whole length 

 of the gland and posteriorly joins its fellow to form an unpaired 

 tube the urinary sinus which opens into the cloaca. This 

 duct has various names none of which are entirely satisfactory. 

 It is called the pronephric, the mesonephric, and the wolffian 

 duct (p. 89). We shall call it usually the longitudinal duct. 

 The collecting tubes of the mesonephros are directed transversely 

 and open at once into the longitudinal duct ; the collecting tubules 

 of the metanephros, the so-called ureters, are directed back- 

 wards and after a certain amount of union amongst themselves 

 open into the hinder part of the longitudinal duct close to the 

 urinary sinus by one or more openings. 



The ovaries and testes are slung to the dorsal wall of the body- 

 cavity by the mesovarium and mesorchium respectively, mem- 

 branes which are either attached close to the mesentery or to 

 the mesentery itself. In some few cases the ovaries of the two 

 sides are united into one body which is placed slightly on the 

 right side. The testes are connected with the anterior end of the 

 mesonephros by a network of tubules the testicular network 

 (Fig. 80), which is not visible (Fig. 81) without special prepara- 

 tion, and which typically consists of the longitudinal canal of 

 the testis, the longitudinal canal of the mesonephros (wolffian 

 body) and the vasa efferentia connecting these two. The longi- 

 tudinal canal of the mesonephros (wolffian body) is connected 

 with the malpighian bodies of a number of the anterior meso- 

 nephric tubules. The number of tubules implicated varies very 

 considerably in different species, and very possibly in individuals 

 of the same species. In Scyllium canicula it appears frequently 

 to be four, in Squatina vulgaris five. The sperm therefore passes 

 through anterior kidney tubules into the longitudinal duct which 

 is in the male much convoluted and functions as the vas deferens. 

 The hind end of the longitudinal duct is dilated to form the vesi- 



