486 PROCEEDINGS OF THE NATIONAL MUSEUM vol.99 



tensis has an especially large one, while in arhynchite of Japan the 

 connection between dorsal and neurointestinal vessels seems to be 

 direct. The absence of a coecum indicates a certain remoteness from 

 Thalasse')na> 

 The males do not differ from females except in the gonads. 



ARHYNCHITE CALIFORNICUS. new species 



Plate 30 



Diagnosis. — Differing from A. arhynchite of Japan (in which 

 proboscis is unknown) in having an indirect connection between 

 dorsal and neurointestinal blood vessels, larger anal vesicles with 

 one or two large frenula; and possibly also in the form of the 

 nephrostomy 



Description. — Body form like a blunt cigar; length 70 to 90 mm.; 

 diameter about 15 to 20 mm. Body wall rather thick, opaque, the skin 

 with small, spaced, unequal, convex glands, which form more or less 

 distinct transverse rows or interrupted rings. Between the glands 

 are very fine transverse wrinkles. At both ends of body the glands are 

 very much larger, often low papilliform, especially ventrally, and 

 much more conspicuous than on middle region of body where they are 

 sometimes nearly obliterated. 



The proboscis, of which there are five detached examples having 

 lengths of 65, 72, 82, and 85 mm., is ribbonlike, thin, and 5 mm. broad 

 at the maximum. The somewhat fan-shaped expanded tip has a thick- 

 ened border, which reappears on the proximal half of the stem, here 

 being scalloped or fluted. The margin closes in and joins close to the 

 base, forming the lower lip. Probably in life the margins meet, 

 forming a tube. The nerve can be easily traced near the margin and 

 follows closely the border of the distal fan, within the thickened por- 

 tion. Also down the center the median blood vessel can be seen in the 

 central mass of longitudinal muscle fibres. At its base the proboscis 

 is constricted and when in place on the animal is surrounded by the 

 ring of papillae (beneath which are strong sphincters) which have 

 been mistaken for lips. The functional mouth is detached with the 

 proboscis and is very small. 



Setae two, close to anterior end, 6.5 mm. long, with a hook very 

 similar to that of inamoenvs (in which setae are 11 mm.) . Interbasal 

 muscle well developed, passing through a small loop of neurointestinal 

 vessel. 



Nephridia two, inserted not quite so close to nerve cord as in 

 inamoenus and behind setae a distance about equal to length of latter. 

 In the type there is an extra nephridium on right side, inserted in 

 front of seta and close to it. Nephridia vary greatly in extent of 



