762 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Genus MYOSOMA Robertson, 1900 



"Zoarium with stolon composed partly of successive polypide-bearing 

 segments and partly of alternate non-polypide-bearing segments; both 

 stalk and calyx muscular, the muscle fibers continuous from one into 

 the other; polypide oblique." (Robertson, 1900:324). Genotype, M. 

 spinosa Robertson, 1900:324. 



The pedicel is unusually thick, flexible, and has a conspicuous set of 

 diagonal muscles in addition to longitudinal ones. The stolon is entirely 

 adnate. 



Myosoma spinosa Robertson, 1900 

 Plate 82, fig. 1 



Myosoma spinosa Robertson, 1900 :324. 



The creeping stolon gives rise to branches vi^hich sometimes unite side 

 by side but more frequently ramify and cross each other, forming a 

 rather close mat; all of the internodes are comparatively short, ranging 

 from 0.20 to 0.70 mm, the infertile internodes 0.08 to 0.12 mm in 

 diameter, the fertile ones somewhat thicker, especially near the origin of 

 zooecial buds. The zooecia arise from the internodes without any special 

 differentiation, and even the muscles extend down into the stolon. The 

 pedicels are exceptionally large, as much as 0.26 mm in diameter, nar- 

 rowing upward to about 0.13 mm below the calyx, varying greatly in 

 height to as much as 2.50 mm. They are highly muscular, with the unique 

 diagonal muscles in addition to the longitudinal ones. 



The calyx is moderately large, ovoid in shape, averaging about 0.65 

 mm long by 0.40 mm in width, the dorsal side more curved ; the lopho- 

 phore is diagonally placed on the shorter ventral side; the tentacle 

 number is apparently 16. Chitinous spines, varying in number, are 

 present on the dorsal side of the calyx and also on the stolon. 



Robertson listed the species from Dillon Beach, Tomales Bay, and 

 from Fort Point and San Diego, California. 



Hancock collections, numerous specimens from Dillon Beach, Cali- 

 fornia, the type locality. Dr. R. J. Menzies, collector. The writer has 

 also taken it at Newport Bay and at La Jolla, California. It is a littoral 

 species and, as far as known, occurs only on the coast of California. 



Genus PEDIGELLINA M. Sars, 1835 



The zoarium is entirely adnate, consisting of fertile and infertile 

 internodes, the latter rather regularly 0.40 mm in length ; lateral stolons 

 sometimes cause the zoarium to cover a considerable area. The pedicel 



