NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 433 



This species is unique in the genus in view of its perforated frontal 

 and imperforate ovicell but, as all other characters agree and no other 

 genus appears to fit it, I leave it where it has usually been assigned. 

 It is fairly common in the arctic and northern seas, extending southward 

 on the Atlantic coast to Cape Cod, Massachusetts. It seems not to have 

 been noted on the Pacific coast. 



Alaska Crab Investigation, entrance to Olga Bay, 40 fms and Leon- 

 ard Harbor, 25 fms, Alaska; Punuk Island, Bering Sea, 15 fms; and 

 Point Barrow, Alaska, 23 fms, Arctic Research Laboratory, G. E. Mac- 

 Ginitie, collector. 



Rhamphostomella gigantea new species 

 Plate 50, fig. 5 



Zoarium encrusting and forming coarse, erect, bilaminate expansions 

 and frills to a height of 25 to 40 mm, yellowish to deep orange in color. 

 The zooecia are among the largest I have ever observed, averaging 1.20 

 mm long (ranging from 1.00 to 1.80 mm), the width ranging from 

 0.65 to 0.80 mm • the depth is correspondingly great, the cavity varying 

 from 0.60 to 0.75 mm and the total thickness about 1.00 mm in full 

 calcification. The frontal is highly arched and excessively thick, with a 

 row of large areolar pores and a vannng number of frontal pores; very 

 strongly costate, the costae often uniting to form a coarsely reticulate 

 surface over the whole front; the ribs sometimes extend to the tip of the 

 avicularian umbo. The avicularium arises at one side but its base is so 

 broad that it often covers nearly the whole width of the frontal; the 

 avicularium is located on the disto-lateral side of a low-conical umbonate 

 process, the mandible slightly more than a semicircle in form, about 

 0.13 mm long and wide. The primary aperture is only slightly asymmet- 

 rical on its proximal border, rounded distally and somewhat straighter 

 on the sides, the length and breadth nearly equal, 0.40 to 0.45 mm. The 

 peristome is moderately low on the sides. No oral spines, no cardelles 

 and no lyrula. Small oval avicularia, similar in size and form to the 

 suboral ones, often occupy the middle of the frontal, mounted on a 

 slightly elevated chamber. 



The ovicells are proportionate in size to the zooecia, averaging about 

 0.65 mm wide by 0.50 mm long, smooth and imperforate, prominent 

 when young but with complete calcification almost entirely immersed. 



Type, U. S. Nat. Mus., 11033; paratype, AHF no. 93. 



Type locality. Point Barrow, Alaska, Arctic Research Laboratory, 

 140 feet. Prof. G. E. MacGinitie, collector. Another colony at a depth 

 of 80 feet from the same locality. 



