NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 389 



Family EurystomellidaC Levinsen, 1909 



Zooecia thick walled, without a covering membrane; without pores 

 or with several large fenestrae; aperture very broad, widest at the 

 broadly concave proximal border. Ooecium enclosed in a kenozooecium, 

 the front with a large membranous area. No avicularia, no spines. 

 (After Levinsen). 



Genus EURYSTOMELLA Levinsen, 1909 



Characters of the family, without frontal pores. Genotype, Lepralia 

 foraminifera Hincks, 1883. 



Eurystomella bilabiata (Hincks), 1884 

 Plate 58, fig. 5 



Lepralia bilabiata, Hincks, 1884:49. 

 Lepralia bilabiata, Robertson, 1908:298. 

 Eurystomella bilabiata, Canu and Bassler, 1923:142. 

 Eurystomella bilabiata, O'Donoghue, 1926:65. 



Zoarium encrusting in a single layer, forming rather coarse layers 

 on stones, shells, etc., reddish or brownish in color. The zooecia are 

 moderately large and very deep, varying much in size, average 0.65 mm 

 long by 0.50 mm wide ; broad and rounded distally, narrowed and trun- 

 cate at the proximal end. The front is a heavy, smooth olocyst entirely 

 without pores, often rising into a broad low umbo. The aperture is 

 shaped like a hat with a very narrow brim, rounded distally and sud- 

 denly wider near the proximal border which is nearly straight; 0.20 

 mm long by 0.30 mm wide. The operculum has the form of the aper- 

 ture, is brown with a darker sclerite which extends all around the 

 border. The ovicell is comparatively quite small, rounded, with a mem- 

 branous area on the top. No avicularia, no spines. 



Described by Hincks from Houston-Stewart Channel and recorded 

 by O'Donoghue for Brotchie Ledge, Victoria, and Bentinck Island, all 

 in British Columbia. Robertson listed it from Puget Sound, Washing- 

 ton, and Mendocino City and Pacific Grove, California. Canu and 

 Bassler recorded it from the Pleistocene of San Pedro, California. 



Hancock Stations: 1176-40, Santa Barbara Island and 1130-40, off 

 Laguna Beach, southern California; 275-34, Navidad Head, Tenacatita 

 Bay, Mexico, 19°12'50"N (the most southern record). I have a speci- 

 men from Nootka Island, Alaska, which is the most northern record. 

 It is a rather common species at low tide on rocky shores from California 

 northward, not frequently dredged, but has been taken at 35 fms. 



