NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 453 



It is an arctic or high northern species, known from northern Norway 

 westward to Prince George Sound (Canadian Arctic) and south along 

 the North American coast to Cape Sable, Nova Scotia (Osburn, 

 1912a :221). 



Point Barrow, Alaska, 22 fms (Prof. G. E. MacGinitie, Arctic 

 Research Laboratory), several colonies. Considering its distribution in 

 the Atlantic south to Nova Scotia, the species may be expected to occur 

 much farther south along the Alaskan coast. Its presence at Point 

 Barrow also suggests that it is circumpolar in distribution. 



Lepraliella bispina (O'Donoghue), 1923 

 Plate 53, figs. 5-7 



Porella bispina O'Donoghue, 1923:41 ; 1926:72. 



The zoarium forms a whitish, shining crust on shells and pebbles. 

 The zooecia (young) are of moderate size, 0.40 to 0.50 mm long by 

 0.30 to 0.40 mm wide, distinct and inflated, the frontal smooth with 

 2 to 4 pores a little removed from the margin ; the primary aperture 

 measures about 0.13 mm in either direction, the proximal border slightly 

 arcuate, the vestibular arch very slightly or not at all beaded ; the 2 

 (rarely 4) oral spines arise distal to the peristome in contact with it; 

 the primary peristome is low and thin. Secondary heavy calcification 

 soon covers nearly all of the primary characters, producing first a nearly 

 level surface, then a granular or nodular one, submerging the aperture 

 on all sides, often with small tubercles. The oral avicularia, often 

 wanting, are small with a rounded mandible, situated usually at the 

 proximal "corner" of the aperture, occasionally at or near the midline, 

 and sometimes one on each side ; these may be submerged in the frontal 

 crust so that they open into the secondary aperture. A secondary sinus 

 or spiramen consisting of a shallow v-shaped notch is usually a little 

 unsymmetrical. Small frontal avicularia similar to the oral ones are 

 irregularly scattered, sometimes numerous, often wanting over consider- 

 able areas. 



The ovicell, 0.20 mm wide, is broader than long, subglobular and 

 prominent when first formed but very soon becomes almost completely 

 submerged in the thick crust; the endooecium bears the usual wide 

 "fissure" next to the orifice, but on secondary calcification this area 

 becomes the subtriangular or semicircular, lightly calcified area similar 

 to that of Rhynchozoon. 



