NO. 2 OSBURN : EASTERN PACIFIC BRYOZOA — CHEILOSTOMATA 461 



The primary ovicell is prominent, hemispherical, smooth with 

 numerous radiating striae and the usual broad, semicircular frontal 

 area above the orifice, width 0.18, length 0.15 mm; with increasing 

 calcification the ovicell becomes entirely embedded. 



In the presence of the tall suboral process and a pair of long oral 

 spines this form is similar to R. bispinosum. It differs in its somewhat 

 smaller size, the smaller size and diliferent proportions of the operculum, 

 the form of the secondary aperture, the absence of the uncinate process 

 at the base of the oral avicularium, the much smaller oral avicularium, 

 and in the shape of the semicircular area of the ovicell which in bispino- 

 sum is subtriangular. 



Type, AHF no. 99. 



Type locality, Hancock Station 1242, Anacapa Island, southern 

 California, 34°02'30"N, 119°2riO"W, at 77 fms. Other localities: 

 Station 1023, Santa Rosa Island, 16 fms; 1130-40, off Laguna Beach, 

 27 fms; 1181-40 Santa Catalina Island, 58 fms, southern California; 

 and San Benito Islands, 44 fms, off lower California, 28°17'15"N, 

 115°35'45''W. There are also two colonies from La Jolla, California, 

 taken on a kelp holdfast, presented by Dr. H. R. Hill. 



Rhynchozoon tuberculatum Osburn, 1914 



Plate 54, fig. 6 



Rhynchozoon tuberculatum Osburn, 1914:200; 1940:442; 1947:39. 



The zoarium is small and comparatively thin. Zooecia small, length 

 0.40 to 0.50 mm, width 0.25 to 0.30 mm, delicate for a member of this 

 genus; the frontal at first smooth but later covered thickly with small, 

 shining tubercles; marginal pores few and small. Peristome high and 

 thin-walled, the secondary aperture ovate; a minute avicularium placed 

 laterally on the inner side, often wanting. Primary aperture ovate, about 

 0.12 by 0.12 mm; at one side immediately above the proximal border 

 an uncinate process (sometimes merely a slender pointed spine) projects 

 often more than half way across the orifice and curves backward ; op- 

 posite this process a small tooth is sometimes present. 



The ovicell is at first prominent, 0.15 mm long by 0.18 mm wide, 

 finely tuberculate like the front in complete calcification; the frontal 

 "triangular area" is small, thin and hyaline: labellum wanting or very 

 small ; a small rounded lucida on each side near the base ; in the presence 

 of the ovicell the peristome is continued forward over the top of the 

 ovicell, above the triangular area. 



