460 University of California Publications in Zoology [Vol. Hi 



Habitat and distribution. — Typically the under sides of rocks in 

 littoral zone on rocky shores everywhere on coast of southern Cali- 

 fornia and probably, though not certainly, as far north as San Fran- 

 cisco, at least. 



Type locality. — La Jolla. 



Polyzoa translucida, n. sp. 



PI. 38, fig. 7; pi. 42, figs. 36 to 38 



Superficial characteristics of the colony. — Composed of zooids 

 joined by short strands to a basal network and, in older colonies, with 

 individuals so close together that considerable portions of the tests 

 of neighboring zooids adhere to each other. Zooids generally roughly 

 egg-shaped although in the largest individuals the two siphons on 

 anterior end may be quite prominent. Zooids colorles,s and semi- 

 transparent (pi. 38, fig. 7). 



Zooids. — Largest 5 to 6 mm. long and 3 to 4 mm. thick. Tests 

 tough, but thin and transparent. Mantle with numerous fine longi- 

 tudinal and transverse muscle fibers. Body consisting of large 

 branchial sac with digestive and reproductive organs located at side; 

 on each .side about opposite the third stigmatie series, an elliptical 

 sac-like body attached to mantle, probably corresponding to the endo- 

 carps of styelids {en., pi. 42, figs. 36 and 37). 



Branchial system. — Branchial siphon 4-lobed, located in middle 

 of anterior end. Atrial siphon also 4-lobed, near branchial siphon on 

 dorsal side of anterior end. Branchial tentacles about thirty, alter- 

 nating long and short. Atrial tentacles about twenty, very small. 

 Branchial sac without folds, with twelve rows of stigmata, each having 

 from thirty to forty stigmata in a half-series ; three longitudinal ves- 

 sels on each side ; greatest number, about fourteen, of stigmata between 

 endostyle and first longitudinal vessel; about eight stigmata in each 

 of remaining intervals. In largest individual fine longitudinal vessels 

 cross the stigmatie series midway between the primary vessels (pi. 42, 

 figs. 36 and 37). Endostyle narrow. Dorsal lamina a plain mem- 

 brane rolled into a tube. Hypophysis a slit-like opening just in front 

 of ganglion. 



Digestive system. — Situated on left side and posterior half of 

 branchial sac. Esophagus (e. pi. 42, fig. 36) aboiit equal in length to 

 stomach ; emerging from branchial sac near its dorsal edge, removed 

 about two stigmatie series from its posterior end. Stomach (.9., pi. 

 42, fig. 36) considerably broader than long, made up of eleven or twelve 

 prominent folds shorter on side turned away from sac. A section of 

 intestinal tract consisting of the esophagus, stomach, and a portion 

 of the intestine about as long as the esophagus, lies in a horizontal 

 position ; organ then bends and runs parallel to its previous course 

 nearly to the dorsum of animal, where it turns anteriorly a .short 

 distance and ends in the bilobed anus. In wall of intestine is a narrow 

 strip running its length, thinner than the re.st of the wall and free 

 from pigment, which is seen to be a groove when viewed from within 

 the cavity of the intestine. A caecum from near pyloric end of 

 stomach is joined by a fine duct to a pyloric gland which ramifies 

 over intestine (pi. 42, fig. 36). 



