﻿SIPUNCULID WORMS OF CALIFORNIA — ^FISHER 407 



(lark-brown thorns occupying middle third of introvert, which is 

 about one-third to one-half body length, depending upon degree of 

 contraction; smooth zone back of tentacles broad, one-fourth to 

 one-third of introvert, reddish brown to purple; no prominent papillae 

 anywhere; tentacular crown strictly dendritic, starting with four 

 major stems, each of which almost immediately divides into two or 

 three branches, and these into others, the crown increasing in com- 

 plexity with increasing size of animal; dorsal blood vessel with a net- 

 work of accessory vessels and with numerous, sometimes branched, 

 long blind Polian tubules. 



Description. — This is one of the chunky pear-shaped Dendi'ostoma, 

 apparently larger in central Califoj-nia than south of Point Concep- 

 tion. Ordinarily large specimens attain 120 mm., exclusive of ten- 

 tacles, but these are small in comparison to an example collected at 

 Bodega Head by Dr. D. M. Wootton. Wlien alive, this giant was 

 195 mm. long, the introvert alone 50 mm.; thickness of trunk 30 mm.; 

 of introvert 15 mm. The introvert is cylindrical, the anterior fourth 

 to third a reddish brown to pui'plish glossy zone, marked by fine 

 circular creases; at the posterior border of this collar is a strong 

 sphincter sometimes indicated by a constriction and a narrow purple 

 zone in preserved specimens. Immediately behind this the middle 

 third of the introvert is occupied by dark brown, well spaced, promi- 

 nent curved spines, directed posteriorly, their bases varying from 

 0.17 to 0.25 mm. in diameter, and their length from anterior edge of 

 base 0.17 to 0.35 mm. Generally, the smaller the specimen the fewer 

 the hooks. Basal third of the introvert is smooth; the surface of the 

 trunk is superficially smooth, very finely and evenly peppered with 

 minute brown spots of two or three sizes (0.07 to 0.1 mm. diameter) 

 which are sometimes tiny eminences. These extend forward as far as 

 the anterior border of the hook zone, but on the introvert are usually 

 colorless. 



Tentacles highly dendritic. Four food grooves lead from the 

 mouth to as many groups of tentacles; each group consists of two 

 main stems, between wliich a shorter branch sometimes assumes 

 the proportions of a major division. Basically there are four tentacles, 

 which by division close to base give the appearance of eight or nine. 

 The tentacles do not give off secondary dendritic branches near the 

 base as do those of zostericolum. Instead, the thin mobile margin 

 of the groove, below the main branches, is produced at intervals 

 into a few slender processes. A specimen 40 mm. long, from Ensenada, 

 has the following number of terminal hranchlets (bearing the ultimate 

 tentacular elements): dorsal tentacles, 32 and 30; ventral, 26, 14. 

 In big specimens the branchlets are much more numerous. 



The two large retractors have their origin in a wide straight attach- 

 ment at the middle of the posterior third of the body, the inner 



