﻿SIPUNCULID WORMS OF CALIFORNIA — FISHER 403 



Descrivtion. — The introvert is partly invaginated ; if fully extended, 

 the animal would measure 92 nmi. in total length; anus to posterior 

 extremity 23 mm. or ono-fourtli total length; greatest width near 

 the posterior end S.T) mm. The l)ody wall is rather thick, opaque; 

 the skin is very glandular, uniformly smooth in appearance, but 

 thickly beset with minute brown subclavate papillae, slightly larger 

 posteriorly (0.06 mm. high). There is no special zone in the anal 

 region, but about 10 mm. in front of the anus, and anterior to the 

 nephridiopores, the papillae become considerably smaller and more 

 crowded (O.l mm. apart), one or two occupying a quadrilateral or 

 irregular area defined b}^ slight creases of the cuticle. Such areas are 

 also to be seen on the trunk, where the papillae usually have a light 

 circular zone at base, becoming transversely elliptical in front of the 

 anus. In addition to the papillae, numerous skin glands open flush 

 with the surface of the cuticle, the pores being of 2 or 3 sizes. Within 

 a square, the sides of which are 0.5 mm., about 25 of these pores are 

 present, and at each corner is a papilla. 



Back of the tentacles is a zone of purple skin, free from papillae, 

 the posterior border plicated. The tentacular crown is more volum- 

 inous than in such species as G. gouldii, although arranged on the 

 same general plan of double series joined by a fold of tissue at the 

 outer edge of the oral disk. There are 16 of these double series, 

 each comprising about 40 tentacles 0.6 to 0.8 mm. long, with the 

 exception of the middorsal double series. This extends nearly to 

 the mouth, forming a loop to enclose the lanceolate nuchal organ. 

 The extended part of this double series carries about 10 extra shorter 

 nuchal tentacles. 



The longitudinal muscle layer is smooth, lustrous, undivided. 

 Retractors two, arising about two-thirds the distance from the anus 

 to the posterior extremity. The base is broad, emarginated, and 

 divided by a deep notch into two parts. The spindle muscle is 

 unattached posteriorly. Fixing muscles F^ and F- anchor the eso- 

 phagus to the body wall. Nephridia short, opening 4 mm. in front 

 of anus. The rectum has a well-developed coecum. The intestinal 

 spiral is relatively large, comprising 68 single coils. 



The contractile vessel accompanies the esophagus to the intestinal 

 spiral and throughout its entire length is provided on each side with 

 Polian villi of characteristic form and arrangement. Just back of 

 the head for a short distance these villi are short, simple, cylindrical, 

 blind tubules. Soon they are bifid at the tip and increase in number 

 until the esophagus leaves the retractor muscles. Then they begin 

 to branch dichotomously twice, then three or four times, and become 

 aggregated in bunches (pi. 26, fig. 5), the branched villi being 0.5 

 to 0.8 mm. long. These clusters form dense masses along each side 

 of the free esophagus between the retractors and the intestinal spiral. 



969586—52 3 



