﻿382 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



e*. Muscle bundles 14 or 15, few anastomoses; body tapers posteriorly 

 to a sharp tail; skin silvery white, rather transparent, with 

 scattered papiUae on body, but in rings near mouth; intestine 

 with 8 to 12 coils; nephridia small, free; ventral retractors arise 

 from two muscles, dorsals from one; no fixing muscle?. 



funafuti (Shipley) 

 e*. Muscle bundles 15 or 16; skin yellowish brown, deepest on introvert; 

 surface rough, especially introvert base and end of body; ventral 

 retractors from muscles 2 and 3 in middle of body, dorsals far 

 more anteriorly from fourth muscle; fixing muscle, with 2 roots, 

 is attached to esophagus; nephridia free, small, deep reddish 

 brown; dorsal lip of nephrostome with 2 or more small processes. 



amamiense (Ike da) 

 cP. Dorsal retractors very weak; ventrals long, arising at commencement 

 of posterior third of body from a single longitudinal muscle; skin 

 very thin with only a few papillae; 18 muscle bundles; intestinal 

 spiral with 16 double loops; spindle muscle strong, with 2 anterior 

 lateral anchors expanded at attachment to body wall; nephridia 

 long, attached by anterior third, nephridiopores slightly behind anus. 



bonhouri (H^rubel) 



b*. Nephridia open posterior to anus (fide Selenka); intestinal coecum 



present; 30 muscle bundles boholense (Semper) 



SIPHONOSOMA IN GENS (Fisher) 



Plates 20, 21 

 Siphonomecus ingens Fisher, 1947, p. 365, pis. 14, 15. 



Diagnosis. — Size very large and body slender, either uniform in 

 thickness or posterior portion contracted, with an attenuate ex- 

 tremity; introvert long; skin smooth, with numerous tiny roundish 

 immersed glands, much fewer and smaller on introvert; longitudinal 

 muscle layer of postintrovert region divided into 20-25 muscle bands, 

 rarely anastomosing; circular layer split into anastomosing fascicles; 

 four retractors, the dorsals arising well in front of ventrals, which are 

 separated from nerv^e cord by two or three muscle bands; postretractor 

 region about half body length; strong spindle muscle of Siphonosoma 

 type arising in front of anus and attached at posterior end of body; 

 intestinal spiral very long (60-62 coils); contractile vessel densely 

 papillated posteriorly; nephridia free, opening a short distance in front 

 of anus; small coelomic papillae forming a transverse zone in front of 

 nephridia; tentacular crown capitate; tentacles arranged in 12 double 

 meridional series, upward of 12 to a series; nuchal organ ver}- small, 

 at anterior end of dorsal double series. Length of type, fully relaxed, 

 500 mm.; diameter 8-10 mm.; introvert about 90 mm.; distance from 

 head to nephridiopores 130 mm.; to anus 140 mm.; to attachment of 

 ventral retractors 215 mm.; to end of intestinal spiral 435 mm. (un- 

 usually extended for preserved specimen). 



Description. — The skin of the preserved specimens is pale yellow or 

 muddy brown. It is closely beset with small, inconspicuous, roundish 



