NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 369 



The ovicell is rounded and prominent at first but soon becomes 

 deeply embedded in the thick crust of the distal zooecium, imperforate 

 and radiately grooved. The secondary layer is incomplete, leaving a 

 rounded area on the top which appears to have a peripheral rovi^ of 

 pores, but the "pores" are merely the bottoms of the grooves at the edge 

 of the covering layer. Width of ovicell about 0.26 mm. 



This species has evidently been confused with another of a different 

 genus (see Schizoporella cornuta) which has the same type of ovicell 

 and oral avicularia but in which the frontal is a tremocyst with numer- 

 ous frontal pores. 



Described by Michelin and later recorded by Busk as a fossil. Known 

 as a recent species from Spitsbergen to Greenland and south to the 

 British Isles. Reported by Robertson from Alaska and by Hincks and 

 by O'Donoghue from various localities in British Columbia, but these 

 records are doubtful. That of Robertson from Alaska may be correct, 

 but Hincks states that "The surface of the younger cells is thickly cov- 

 ered with minute punctures," which is not a character of Stephanosella. 



Not taken in the Hancock dredging but collected by MacGinitie at 

 Point Barrow, Alaska, (Arctic Research Laboratory). It appears to be 

 a circumpolar and northern species. 



Stephanosella vitrea new species 

 Plate 42, figs. 6-8 



Zoarium small, encrusting, especially on stems, worm tubes, etc., 

 vitreous or porcellanous, the surface often rough. Zooecia small, 0.30 

 to 0.45 mm long by 0.25 to 0.35 mm wide, distinct only when very 

 young. The frontal is a smooth vitreous olocyst which later becomes 

 very thick and irregular, except for a small area around the aperture; 

 a few small areolar pores and occasionally a few additional ones irreg- 

 ularly situated; with the thickening of the olocyst the pores are some- 

 times carried up on the front. The aperture, always clearly visible even 

 in highly calcified specimens, varies slightly in dimensions but averages 

 about 0.10 mm wide by 0.11 mm long, nearly round back to the car- 

 delles, proximal to which is a v-shaped sinus ; the sinus also varies some- 

 what, occasionally almost slit-like. The peristone is low, smooth, without 

 spines, and is not involved in the secondary thickening of the front. 

 The operculum has the form of the aperture, moderately chitinized with 

 a narrow, thickened border, the muscle attachments distant from the 

 margin. There is a pair of small oral avicularia with a pointed (some- 



