222 



W. HAROLD LEIGH-SHARPE 



NOTIDANUS (HEXANCHUS) GRISEUS 



The six-gilled shark 



This primitive Protoselachian fish exhibits, as may be supposed, 

 characters quite different from those of the species previously- 

 considered. I was fortunate enough to be able to investigate a 



Ph. CI. 



Fig. 1 Notidanus griseus. Sh., prolongation of the pelvic fin forming a 

 sheath for the clasper; Sh. S., sheath sac; Ph. CI, phyllaceous clasper. 



large specimen measuring 77 inches, or nearly 2 meters, in length, 

 taken in Japan, in 1905, and from this the figures are drawn. I 

 have also examined small specimens from Nice, and in these 

 the claspers are of a bright lemon-yellow color. 



The pelvic fins are prolonged posteriorly in such a way as to 

 form a sheath in which the claspers are effectually concealed, 

 so that, at first sight, the small specmiens may be mistaken for 



