ECHIUROID FAUNA OF NORTH PACIFIC — FISHER 485 



moderate length. The whole complex in a relaxed specimen appears 

 to be moved far forward and to be dominated by the setae and their 

 numerous muscles. I was unable to find the coecum in the type, 

 but in another specimen there is a very small spongy body in the 

 proper location. In L. felodes it is of normal size. 



The vascular system differs from that of L. fclodes in respect to 

 the neurointestinal vessel which has no loop surrounding the inter- 

 basal muscle of setae and does not divide into two until it reaches 

 the gut, where the ring vessel is inconspicuous. 



Ty^e.— U.S.N.M. No. 21079. 



Tyye locality. — Albatross station 4339, off San Diego, Calif., 287- 

 369 fathoms, green mud, March 10, 1904 ; 4 specimens. 



Genus ARHYNCHITE Sato 



Arhynchite Sato, 1937, p. 142 (type, Thalassema arhynchite Ikeda). 



Diagnosis. — Proboscis deciduous, long, slender, ribbonlike, with a 

 small, expanded, fan-shaped extremity, and a closed base forming 

 lower lip ; nephridia two, the nephrostome with one lip prominently 

 produced, leaf like and with an irregular or laciniate margin; ali- 

 mentary canal very long, the presiphonal segment two to three times 

 body length, with or without a ciliated groove; blood system with or 

 lacking a ring vessel; no coecum; anal vesicles Thalassema-like; 

 muscles of body wall smooth with no concentration of fibres into 

 bands ; setae two, with interbasal muscle. 



Remarks. — The discovery of a well-developed proboscis in two 

 species is interesting to say the least. Ikeda examined carefully a 

 number of specimens from Sapporo and was convinced that a proboscis 

 was not present, while Sato sectioned the mouth region. "No trace 

 of a detached proboscis was found, and thus the mouth opening was 

 entirely enclosed by means of the papillae which were regularly 

 arranged around the mouth"' (1937, p. 145). What Sato did not do 

 was to trace the ventral nerve to ascertain if it formed a ring around 

 the mouth, the only real test. I dissected one of the specimens of 

 calif ornicus and found the nerve cord to be ruptured at the point 

 where it divides into two. But superficially there is no hint that a 

 proboscis has been detached, and this was true also of A. inamoenus, 

 which I described in 1946 (p. 247) . 



I think the discovery of a proboscis in the two species herein 

 described need not invalidate the genus. The nephrostome and the 

 very long presiphonal segment of the intestine separate the group 

 from Thalassema. Also the form of the proboscis is different from 

 that of Thalassema. The absence of a ring vessel in inamoenus and 

 californicus would be a useful distinction but unfortunately puget- 



