56 



rlo-lit is tliicker. The ovaries are not suspended by membranes (mesoaria) as in 

 symmetrical fishes, but lie like kidneys beneath the peritoneum which passes over 

 them. Morphologically the mesoarium may be considered to have fused with the 

 surface of the median partition which separates the lateral body cavities from one 

 another. Or, to regard the evolution in a different way, it may be that the ovaries 

 have grown back post-anally beneath the peritoneum. Each ovary has a containing 

 wall which is independent of the peritoneum, though attached to it : the latter can be 

 separated from the former with facilitj'. The ovarian artery and vein pass down together 

 on each side from the posterior end of the main body cavity, and run along the dorsal 

 side of each ovary. The walls of the two ovaries unite anteriorly on the ventral side 

 of the main body cavity to form a single wide tube which opens to the exterior behind 

 the anus and conducts the ova to the exterior. When the ovary is cut open the 

 germinal surface covered with projecting ovigerous lamelte having a general 

 longitudinal direction, is seen to extend all round the internal surface except along 

 the median ventral line, where the surface of the ov&rian wall is quite smooth and 

 destitute of ovigerous lamellae : this probably represents the suture along which in 

 development the edges of the ovarian lamina joined together to form a tube. 



On the dorsal wall of the main body cavity the renal organs form a broad reddish band, 

 placed in the centre and symmetrical^, the two kidneys seem to be fused together in 

 the middle line. No part of the renal mass is continued into the right lateral body 

 cavity, but it is continued as a bulging thick mass into the dorsal part of the left 

 lateral cavity, where it is in contact ventrall}^ with the left ovary. From the ventral 

 anterior corner of this mass there comes off a single short renal duct which opens out 

 into a large urinary vesicle. This vesicle sends a prolongation backwards between 

 the left ovary and the waU of the left lateral cavity, and it extends downwards behind 

 the common oviduct, between this and the wall of the main body cavity, to open to 

 the exterior on a small pajjilla on the right side. The opening of the oviduct, 

 although in the same depression of the skin as the anus, is separated from the 

 latter by a fold of membrane. Anteriorly the kidnej's extend beyond the main body 

 cavity between the oesophagus and the muscles dorsal to it, as far as the posterior 

 surface of the skull. 



Description of the Viscera of the male from a specimen 1 foot long (2>\ cm.). 



Plate IX. 



The intestines are arranged as in the female except that they do not reach quite so 

 far back in the right lateral body ca\dty, that is, they are slightly shorter. In front 

 of the bend which divides the colon from the ileum, is seen the urinary bladder, 

 distended. No part of the testes is seen without disturbing the organs in the body 



