NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 511 



coarser, with a more elongate aperture and larger zooecia and ovicells. 

 In the Arctic Ocean this species has been recorded from Spitsbergen 

 westward ; it is common in Greenland waters and south on the Atlantic 

 coast to Nova Scotia. The writer (1921:452) has listed it from the 

 Pribilof Islands in the Bering Sea. Hincks recorded it from British 

 Columbia; Robertson had it from the Pribilof Islands to northern 

 California, and O'Donoghue added numerous British Columbia records. 

 It did not appear in the Hancock dredgings, but there are specimens 

 in the collection from Cleveland Passage, Alitak Bay and Big Koniuji 

 Island, Alaska, the last two collected by the U. S. Alaska Crab 

 Investigation. Common at Point Barrow, Alaska, Arctic Research 

 Laboratory, G. E. MacGinitie, collector. 



Costazia ventricosa (Lorenz), 1886 

 Plate 63, figs. 4-5 



Cellepora ventricosa Lorenz, 1886:14. 

 Cellepora ventricosa. Waters, 1900 :96. 

 Costazia ventricosa, Osburn, 1932:16. 



Zoarium encrusting on pebbles, shells and occasionally on algae, more 

 or less nodular on stems but covering considerable areas on stones, 

 occasionally erect and branching; the large projecting zooecia giving a 

 rough appearance. The zooecia are erect, except at the growing edges on 

 stones where they are somewhat procumbent; large (0.55 to 0.70 mm 

 long in the procumbent zooecia, usually about 0.55 mm across the erect 

 ones), prominent and very distinct. The frontal is very thick, with 

 two or three rows of large infundibuliform pores which are carried 

 up around the peristome in final calcification, often rising above the 

 level of the operculum ; the frontal wall fuses with the peristome to form 

 a thick, rough border which does not rise much above the level of the 

 operculum. The lateral oral avicularia, with semicircular mandible, rise 

 above the level of the peristome and are inflected tow^ard the aperture; 

 they are often wanting. Interzooecial avicularia are apparently wanting, 

 as Lorenz and Waters did not observe them in the European Arctic 

 and I have not found them in specimens from Arctic America and the 

 Pacific coast. 



It is the largest and roughest of the Costazia species and, as Waters 

 states (1900:96) "can be distinguished by the naked eye." 



The ovicells are large, hemispherical, about 0.40 mm wide by 0.26 

 mm long. Lorenz states that they are easily overlooked on account of 

 their small size and they often have a single median pore, while Waters 

 says that the ovicell is imperforate. In earlier stages the ovicells are 



