BLOOD-VASCULAR SYSTEM OF THE TILE-FISH. 



109 



IV. THE CAUDAL VEIN AND VKN.K ADVEHENTES RENALES. 



The caudal vein {35) is situated in the haemal canal just ventral to the caudal 

 aorta. After receiving branches from the caudal fin {39) it collects blood from the 

 tail region by means of ventral {38), dorsal (°29). and intermuscular {30) veins. These 

 are received opposite every other vertebra, and alternate with the arteries. After 

 leaving the haemal arches at the caudal extremity of the kidney the caudal vein 

 divides into a right {36d) and a left {36s) branch. The right branch is short {36A) 

 and opens directly into the right cardinal vein. The left branch {36s) runs forward 

 in the substance of the kidney as an advehent vein, which, according to Parker (1884), 

 is the remains of the posterior portion of the left cardinal vein. 



Four veins empty into the enlarged posterior division of the kidney, two from 

 each side of the body. The posterior pair (■!'/) return blood from the ventral muscles 

 just behind the cloaca, while the anterior pair {33) return blood from the posterior 

 lateral muscles of the abdomen. 



The parietal veins in the abdominal region consist of dorsal, intermuscular, and 

 peritoneal branches. The dorsal ("■) to 29") and intermuscular branches {30) are 

 received opposite every other vertebra, alternating with the arteries. The peritoneal 

 branches (.;/) return blood from the lateral walls of the abdomen, and. in addition, 

 each peritoneal vein receives a vessel {32) from the dorsal surface of the swim- 

 bladder. The parietal veins in the abdominal region either enter and break up in 

 the substance of tin 1 kidney as vena? advehentes {31') or, after sending out advehent 

 branches, connect directly with the right cardinal vein {31). 



REFERENCES TO FIGURES. 



d. ami s. denote dextra and sinistra, respectively. 



A., auricle. 



At'., anal fin. 



Ar 1 ., first aortic rnot. 



Ar 2 ., second aortic root. 



B., branchial arch. 



Ba., bulbus arteriosus. 



Da., dorsal aorta. 



Df. , dorsal fin. 



]•:.. eye. 



II.-., Hsemal spine. 



K., kidney. 



K'.. cranial portion of kidney. 



L., liver. 



Xs., neural spine. 



CEs., oesophagus. 



P. D., pterygiophore of dorsal (in. 



I's., pseudobranch. 



P. V., pterygiophore of anal tin. 



V., ventricle. 



Va., ventral aorta. 



ARTERIAL SYSTEM. 



V to IV. First to fourth afferent branchial arteries. 



/. Recurrent branch to ventral most filaments. 

 I to IV. First to fourth efferent branchial arteries. 

 I. First efferent branchial artery. 



i. Branch for dorsalmost filamentar vessels. 

 3. Hyoidean artery. 



.;. Muscular branch. 



.■;. Nutrient branch to first Liill arch. 

 G. Lingual artery. 



7. Branch to branchiostegal membrane and rays. 

 <■>'. Muscular branch to angle of mouth. 



9. Opercular branch. 



10. Afferent pseudobranchial artery. 



