228 



THE ELASMOBRANCH FISHES 



Beginning with the twenty-fifth spinal nerve {sp. 25, fig. 205) , the terminal 

 divisions of some of the spinal nerves are connected at the region of the lateral 

 abdominal vein (l.a.v.) into a nervous collector. This in Hepfanchus cinereus 

 as described by Braus (1898) forms a collector of iiniisnal length, which 

 continues to the thirty-eighth spinal nerve {sp. 38), but does not perforate 

 the cartilage of the pelvic girdle. 



Posterior to the pelvic girdle a pelvic plexus of nerves {pi. p., fig. 205) is also 

 found in Heptanchus. This plexus in the adidt Heptanchus cinereus usually 

 involves only the forty-eighth and forty-ninth nerves, and the plexus thus 

 formed is considerably back of the pelvic girdle. 



Fig. 205. Nervous collector, Heptanchus cinereus. (From Braus.) 



l.a., lateral artery; l.a.v., lateral abdominal vein; php., pelvic plexus; sp. 25, 38, twenty - 

 fifth and thirty-eighth spinal nerves. 



