NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 459 



avicularian chamber ; occasionally additional low pointed tubercles appear 

 on the lateral border of the peristome. Spines are entirely lacking. 



The ovicell at first is subglobose, about 0.20 mm wide, the length 

 less than the width, but it very soon becomes buried within the thick 

 frontal crust. The area above the orifice is nearly semicircular, with 

 often a short labellum extending nearly across above the orifice. 



The avicularian mandibles are of 3 kinds, the long-triangular sub- 

 oral, the long-triangular and acuminate frontal and the short-triangular 

 (almost equilateral) frontal; the area below the lucida with sharp outer 

 corners. The operculum is shaped much like that of R. rostratum, but 

 the points of attachment are much closer together. 



Described from Cumshewa, British Columbia, and later recorded 

 by O'Donoghue from numerous British Columbia localities. Robertson 

 lists it from San Diego to San Pedro, California, but as R. rostratum 

 is also common in this region she may have had both species. 



Hancock Stations: Dredged at 45 stations from the coast of Oregon 

 southward to San Benito Islands, Lower California. Abundant in 

 Puget Sound and all along the coast southward to the Channel Islands 

 ofJ southern California, shore to more than 100 fms. 



Rhynchozoon grandicella Canu and Bassler, 1923 

 Plate 54, figs. 7-8 and 11 



Rhynchozoon grandicella Canu and Bassler, 1923:156. 



Zoarium encrusting on shells, pebbles, etc. Zooecia large (young 

 zooecia at the edge 0.65 to 0.85 mm long by 0.40 to 0.55 mm wide, 

 much smaller near the center of the colony) ; distinct and considerably 

 inflated, irregularly ovate, with numerous small marginal pores between 

 which low costal ridges radiate toward the center. The primary aperture 

 is broader than long (0.16 mm wide by 0.13 long) with a shallow 

 rounded sinus on the proximal border, the vestibular arch coarsely 

 beaded ; the operculum thin, without marked sclerites and with a lightly 

 pebbled surface. Two minute oral spines are occasionally present. A 

 large suboral avicularium is always present at one side of the midline 

 and overhanging the aperture; the mandible, directed laterally, is 

 elongate-triangular, strongly hooked, its borders dark brown and its 

 length varying from 0.13 to 0.20 mm. At the inner corner of the 

 avicularian base is a strong uncinate process, opposite this process there 

 is usually a small pointed projection and between these is the rounded 

 spiramen. Frontal avicularia are frequently present, similar to the 

 suboral ones but smaller and mounted on a large chamber. 



