VEINS OF FISHES. 



465 



308 



a single file of blood-discs, and connecting the termination of the 

 arteries with the commencement of the veins, figs. 328, 329. 



The vertebral system of veins commences by a series of capil- 

 lary roots in the integnmcnts and muscles, which unite to form 

 branches corresponding with the muscular and osseous segments 

 of the body : these ' segmental ' veins consist, in the tail, of upper 

 or neural, and lower or htemal 

 branches; in the abdomen, of 

 upper and lateral branches ; in 

 the head, where the vertebral 

 segments are more modified, the 

 veins manifest a less rcgndar 

 and apprccialjle correspondence 

 with these segments. The ce- 

 phalic veins, returning the blood 

 from the cranial vertebrae, their 

 apjiendagcs and surrounding 

 soft parts, from the brain, the 

 organs of special sense and their 

 orljits or proper cavities, from 

 the mouth and pharynx, and, 

 receiving also the whole or part 

 of the ' vena3 nutritire ' from the 

 branchial arches, unite together 

 on each side to fovea a pair of 

 ^jugular' veins, fig. 308,7;*, each 

 of which usually t[ilates into a 

 larger sinus, and aeain contracts 

 and resumes the vasiform cha- 

 racter, as it descends to beneath 

 the parapophyses of the atlas 

 and axis, in order to join the 

 corresponding trunk of the ver- 

 tebral veins of the liody. ' This 

 great trunk, called ' vena cardi- 

 nalis,' ^ fig. 308, v, commences L^' 



at ■ the base of the tail-fin, 

 where it receives blood, and some affirm also lymph, from the pul- 

 sating sac there present in the Eel-tribe. The vein-trunk is 



' 111 tlie Lamprey the corresponding jugular trunks lie above the aponeurotic repre- 

 pentatiyes of the vertebral parapophyses, 



^ ' La vcine cave ' of Cuvier; but it is not homologous with either the ' inferior ' or 

 * superior vcnaj cava; ' of Man. 



VOL. I. n II 



Circulation of the l>lood in the FJsb. ccLxvr. 



