Stenhouse. — On the Anatomy of the Pig-fish. 119 



in the posterior dorsal body-wall : the ureters can only with 

 difficulty be distinguished from the gonaduct. In the male, a 

 urinary bladder can always be seen on the right side ; in the 

 female it is obscured, except immediately after the spawning- 

 season, when its external aperture may also be distinguished 

 from that of the gonaduct. 



D. ClKCULATORY SYSTEM. 



Arteries. — The very short ventral aorta is continuous with 

 a small median vessel supplying the branchial arches. On 

 each side the first two efferent branchial arteries unite to form 

 the first epibranchial, the second being formed by the third 

 and fourth efferent vessels. The first efferent branchial has a 

 large branch piercing the prootic, and apparently, with its 

 fellow, completing a circle above the parasphenoid. The epi- 

 branchials unite to form the dorsal aorta, which very soon 

 gives off, together, two subclavian arteries, and a large coeliaco- 

 mesenteric artery running downwards and backwards past the 

 right side of the stomach, to divide finally into two main 

 trunks : of these, one supplies mainly the retia mirabilia of 

 the air-bladder, but also, partly, the stomach ; while the other 

 gives off a gastro-hepatic branch, and then supplies all the 

 other viscera. Above the posterior air-chamber the aorta gives 

 off branches ramifying in the walls of that organ ; also, a little 

 farther back, the spermatic artery. 



Veins. — The portal vein is formed by two main factors, one 

 mesenteric, the other draining the retia mirabilia and the 

 stomach. The caudal vein is apparently not connected with 

 the cardinals except by renal capillaries. A median vein 

 from the functional kidney receives the spermatic veins, and 

 then divides into two cardinal veins, of which the right is the 

 larger. The veins, like the arteries, of the posterior air- 

 chamber are not connected with the mesenteric, but open into 

 the cardinal veins, which, after forming each a sinus in the 

 pronephros, meet the hepatic and large subclavian veins and 

 open into the sinus venosus. 



EXPLANATION OF PLATES X.-XIII. 



Agriopus leucopoecilus . 



(Cartilages are dotted and symphyses lined.) 



Plate X. 

 Fig. I. Side view : bones of head and limb-girdles. 



Plate XI. 

 Fig. II. Skeleton of head — dorsal view. 

 Fig. III. „ ventral view. 



Fig. IV. Internal aspect of limb-girdles. 



