﻿404 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



The vessel and villi are pale orange and are packed with hemispherical 

 corpuscles, 0.01 mm. in diameter, having one side invaginated. 



Ty^e.— U.S.N.M. No. 21223, sandspit, in Zostera, January 1930, 

 G. E. MacGinitie. 



Type locality. — Newport Bay, Orange County, Calif. 



Genus DENDROSTOMUM Grube 



Dendrostomum Grube, in Grube and Oersted, 1859, p. 118. 



Dendrostoma Keferstein, 1865a, p. 207 (emendation of Dendrostomum) . — Authors 

 since 1865. 



Diagnosis. — Distinguishable from other sipunculoids by their four 

 to eight conspicuous, often several times dichotomously branched, 

 grooved tentacles, which carry numerous small tentacules, pinnately 

 or palmately arranged. Oral disk with four primary food grooves, 

 which branch to the tentacles; inner longitudinal muscle layer of 

 body wall continuous, not separated into bands; usually two retractor 

 muscles; a strong spindle muscle attached near anus but not pos- 

 teriorly; typically three fixing muscles or intestinal anchors; two 

 nephridia not anchored by mesenterj^; contractile vessel with a few 

 to very many, long or short Polian tubules; hooks or spines on 

 introvert present or absent. 



Remarks. — The California Dendrostoma are all large species, and 

 with the exception of hexadactylum are found between tide marks. 

 D. pyroides lives by preference and attains greatest size in clefts of 

 rocks, especially granite, where it apparently maintains a permanent 

 residence, retreating far from the surface when the tide is out. D. 

 perimeces, the longest of all, is an estuarine form dwelling in muddy 

 sand. It also lives off shore in deeper than intertidal water. D. 

 zostericolum is found among eelgrass roots and in sandy mud among 

 rocks, in bays, and on the open coast. D. dyscritum has been en- 

 countered on the open coast in fissures of rock where mud and sand 

 can accumulate and where the deeper parts may be black from 

 sulphur compounds. It also occurs off shore. 



It is difficult to describe the shape of these animals since, when 

 alive, they can stretch their bodies to an astonishing degree. Even 

 when killed "extended," with tentacles expanded, there is much 

 variation. However, such species as zostericolum and perimeces are 

 obviously longer than the others and assume a more cylmdrical 

 form when carefully killed, while pyroides and dyscritum are likely 

 to be swollen posteriorly and hence are more pyriform. 



The California species have bushy tentacles, branched dicho- 

 tomously several times, although the branches of such dichotomy 

 are not necessarily equal. A typical crown, drawn from fife, is shown 

 on plate 28, figure 1. In some extralimital species, e. g., D. blandum, 



