428 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



It is a common arctic and northern species, occurring on the Atlantic 

 coast as far south as Cape Cod, Massachusetts ; abundant in the waters 

 about Greenland, and recorded as far west as Icy Cape, Alaska (Osburn, 

 Canadian Arctic Exped.)- It has not been reported south of Alaska, 

 except for O'Donoghue's record of R. porosa at Cape Ebenshaw, British 

 Columbia. O'Donoghue recognized the similarity to bilaminata, but 

 the distinguishing characters which he indicates for porosa (viz., "the 

 far larger size of the rostrum and peristome") are within the range of 

 variation of bilaminata. 



U. S. Alaska Crab Investigation, Leonard Harbor, Alaska, station 

 60-40, at 25 fms ; also at Point Barrow, Alaska, Arctic Research Labora- 

 tory, down to 23 fms. G. E. MacGinitie, collector. 



Rhamphostomella hincksi Nordgaard, 1906 

 Plate 50, fig. 3 



Rhamphostomella hincksi Nordgaard, 1906:31. 

 Cellepora plicata, Hincks, 1877:106. 



Zoarium encrusting on various surfaces. Zooecia moderately large, 

 0.70 to 0.85 mm long by 0.45 to 0.55 mm wide: frontal somewhat 

 inflated, smooth, with a row of conspicuous areolar pores between 

 which costal ribs run up for a short distance on the front (occasionally 

 to the base of the rostrum) as noted by Hincks and Nordgaard. The 

 primary aperture is nearly round, about 0.26 mm in either dimension, 

 a little narrower and slightly asymmetrical proximally, and without 

 either cardelles or lyrula (as noted by Nordgaard). Proximal to the 

 aperture and asymmetrically placed is a moderate-sized bulbous avicu- 

 larian chamber, the rostrum high and extending somewhat over the 

 aperture; the distal wall of the rostrum is nearly straight and set at an 

 angle to the midline and a peristomial lappet is directed in the same 

 manner on the opposite side so that the secondary aperture is angulated 

 proximally (a condition which no doubt led Hincks to place this species 

 under R. plicata). The mandible is short-spatulate or a little narrowed 

 terminally. 



The ovicell is large, 0.35 to 0.40 mm wide and 0.30 to 0.35 mm 

 long, prominent, smooth or roughened around the sides, with several 

 frontal pores and the area above the orifice a little flattened. 



The complete absence of lyrula and cardelles seems to ally this species 

 with R. scabra (Fabricius) rather than R. plicata (Smitt). 



