558 



DISCOVERY REPORTS 



proboscis is about o-y-o-Q mm. long and 0-3 mm. in diameter. It bears 14 longitudinal 

 rows of 8-10 hooks each. As is characteristic of the genus, the hooks in the ventral rows 



-^ 



0-2 MM. 

 Fig. 15. Rhadinorhynchtis wheeleri . Anterior end of female, lateral view. 

 </., dorsal proboscis-hook; s., body-spine; v., ventral proboscis-hook. 



0-2 MM. 

 Fig. 16. Rhadmorhynchmjohm. 

 Anterior end of female, 

 lateral view, d., dorsal pro- 

 boscis-hook; s., body-spine; 

 v., ventral proboscis-hook. 



are much larger than those in the dorsal rows. The former (measured in a straight line 

 from tip to insertion) reach a length of about 0-15 mm., while the latter are only about 

 o-o6 mm. long. The spines on the anterior portion of the body are small (0-025- 

 0-03 mm. long), and are arranged in fairly regular transverse ventral rows, extending 

 well round on to the lateral surfaces. The proboscis-sac is about 1-1-3 mm. long. The 

 lemnisci are apparently short, oval sacs. The eggs measure about 0-09 mm. x 0-025 mm. 

 Of the species of Rhadinorhynchus already known, R. pristis (Rud., 1802), R. horridus 

 (Liihe, 1912) and R. tenuicornis Van Cleave, 1918, are said to possess 14 longitudinal 

 rows of hooks on the proboscis. The two first-mentioned species are much larger than 

 the present form, while in all three the number of hooks per row is much larger (26 in 

 pristis, about 26 in tenuicornis, 31 in horridus). Indeed, in no species oi Rhadinorhynchus 

 hitherto described, so far as the writer is aware, is the number of hooks in each row less 

 than about 20. 



Rhadinorhynchus johni, sp. n. 



(Fig. 16) 



This second species of Rhadinorhynchus occurred in the rectum of a hake {Merlucciiis 

 sp.) off the Falklands (Station WS 73), March 7, 1927. 



