NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 183 



Zoarium encrusting on shells, one colony covers an area 20 by 25 mm, 

 light reddish brown in color. The zooecia are large, averaging 0.78 mm 

 long by 0.47 mm wide, very regular in arrangement. The pericyst is 

 thick, formed of about 7 pairs of costae, the proximal ones radiate and 

 the distal ones transverse; the distal pair of costae unite to form the 

 proximal border of the aperture which is a little elevated and sometimes 

 forms a low mucro. The aperture measures about 0.25 mm in width by 

 0.17 mm long, roughly semicircular, straighter on the proximal border. 

 The peristome is low, with four short, strong, flattened spinous processes 

 which bend slightly over the aperture; the proximal pair, usually smaller, 

 are opposite the proximal border of the aperture, the distal pair opposite 

 the distal end of the aperture. The costae are strong with three to five 

 irregularly rounded lacunar pores between ; the lumen pores usually two. 



The ooecium is large (0.40 mm wide), the front usually a little 

 flattened with a narrow keel and a few pores, partially embedded in the 

 base of the distal zooecium. The distal pair of spinous processes unite 

 more or less with the front of the ovicell, but do not enter into its forma- 

 tion; instead they "form two outspread wings overhanging the oral open- 

 ing." (Norman, p. 104). The fertile zooecia are not reduced in size (as 

 in C. annulata) but are similar in all respects to the others, except for 

 the slightly wider aperture. 



In raising this form to specific rank the following characters are of 

 importance: the large size of the zooecia (noted by Waters and Norman), 

 the replacement of spines of annulata by broad processes with the proxi- 

 mal pair in a different position, and the nature of the ovicell which is 

 very much larger, of diflferent form and not surrounded by a small keno- 

 zooecium. For these reasons also, as well as the agreement with Reginella 

 jurcata, the species is transferred from Crihrilina to Reginella. Waters, 

 under Cribrilina annulata, noted the presence of the lateral oral processes. 

 These structures are homologous to the costae and in series with them 

 but are short and nearly erect. Norman considered it a variety of annu- 

 lata but questioned whether it should not be "regarded as a species." It 

 has been recorded from Franz-Josef Land, Spitzbergen, Greenland and 

 the White Sea. No doubt it is circurapolar in distribution, and it has not 

 been observed out of the high Arctic region. 



Collected by Prof. G. E. MacGinitie at Point Barrow, Alaska, several 

 colonies on shells, at 22 fms, Arctic Research Laboratory. 



