﻿SIPUNCULID WORMS OF CALIFORNIA — FISHER 381 



tures, they are of little value in determining species and are perhaps 

 absent in small species having a thin body wall. 



The genus contains about 24 nominal species, wliich fall into 3 

 fairl}'^ natural groups: Subgenus Siphon o soma, sensu stricto (p. 381); 

 subgenus Hesperosiphon Fisher (p. 386) ; subgenus Dasmosiphon Fisher 

 (p. 386). 



Subgenus Siphonosoma, sensu stricto 



Diagnosis. — No dissepiments in body cavity; rectum devoid of 

 numerous elongate diverticula. The following species are included: 



Spinelets on introvert Devoid of spinelcts on introvert 



arcassonense (Cuenot). amamiense (Ikeda). 



australe (Keferstein), type. boholense (Semper). 



eniwetoki Fisher.® honhouri (H6rubel) . 



pescadolense Sato. dayi Stephen. 



takasukii Sato. junajnti (Shipley). 



ingens (Fisher). 



mourense Sato. 



novae-pommeraniae Fischer. 



rotumanum (Shipley). 



KEY TO SPECIES OF SUBGENUS SIPHONOSOMA LACKING SPINES ON INTROVERT 



o*. Retractors arise from body wall at same level; intestinal coecum present. 



novae-pommeraniae Fischer 

 a^. Retractors arise at different levels. 



fcJ. Nephridia open on same level as anus or slightly in front; no intestinal 

 coecum. 

 c'. Muscle bundles 20 or more. 



d>. Small scalelike papillae on introvert dayi Stephen 



(P. No scalelike papillae on introvert. 



e^. Circular muscles not divided into fascicles; fixing muscle anchors 



rectum mourense Sato 



€*. Circular muscles divided into anastomosing fascicles; fixing muscle 



anchors esophagus _ ingens (Fisher) (p. 382) 



c*. Muscle bundles 18 or less. 



d\. Dorsal retractors well developed, not very small. 



e*. Muscle bundles 14; skin glistening gray with certain blackish papUlae 

 scattered over surface becoming closely and regularly arranged 

 on introvert; circular muscles in rings with numerous anastomoses; 

 anus conspicuous; ventral retractors very long, originating from 

 second and third longitudinal muscles; intestine with 30 to 40 

 coils; no fixing muscle? rotumanum (Shipley) 



• Siphonosoma eniwetoki Fisher, 1950b, p. 805.— Diflcrinp from S. australe (Xeferstein) in having less 

 prominent skin glands in anal region and at end of body; much smaller and blunter introvert hooks; thinner 

 body wall; an esophageal fixing muscle attached to midventral line. Length of contnicted specimen 106 

 mm., plus invaginated introvert, 35 mm.; thickness at middle of body 15 mm.; 16 to IS rather broad lon- 

 gitudinal muscles, occasionally anastomosing; ventral retractors from muscles 2-3 or 2; tV.e dorsals from 3-4; 

 a fixing muscle to esophagus and one to rectum; intestinal coecima; nephridia small, free; color rosy gray. 

 Type, U. S. N. M. No. 21128, Bogen I.«land, Eniwetok Lagoon, Marshall Islands, Intertidal. 



