NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 427 



Rhamphostomella fortissima Bidenkap, 1900 

 Plate SO, figs. 1-2 



Rhamphostomella fortissima Bidenkap, 1900:524. 

 Discopora scabra van fortissima, Nordgaard, 1918:78. 



This species bears a close resemblance to R. costata in the younger 

 stages and the measurements are close, though in our specimens the 

 primary aperture is somewhat larger (about 0.26 mm in either dimen- 

 sion). Possibly Nordgaard is correct in giving it merely varietal status, 

 but in our specimens the costae do not extend beyond the base of the 

 umbo, the secondary calcification is much heavier, and raised frontal 

 avicularia of huge proportions are abundantly distributed over the surface. 



Recorded by Bidenkap and Nordgaard from Spitsbergen and several 

 of the northern fjords of Norway. 



Point Barrow, Alaska, 23 fms, Arctic Research Laboratory, Prof. 

 G. E. MacGinitie, collector, several colonies. 



Rhamphostomella bilaminata (Hincks), 1877 

 Plate 52, fig. 10 



Cellepora bilaminata Hincks, 1877 :1 1 1. 

 Rhamphostomella bilaminata, Lorenz, 1886:13. 

 Discopora bilaminata, Levinsen, 1916:461. 

 Rhamphostomella bilaminata, Osburn, 1923 :10D. 

 Rhamphostomella porosa, O'Donoghue, 1923 :45. 



Zoarium encrusting on various surfaces, frequently on hydroid 

 stems where they rise into bilaminate folds. Zooecia of moderate size, 

 0.65 to 0.75 mm long by 0.40 to 0.45 mm wide; the front nearly flat, 

 smooth or with short costae which do not run to the base of the 

 umbonate process, areolar pores large but indistinct because of the 

 crowding together of the zooecia. The primary aperture is rounded, 

 about 0.20 mm in either dimension, the proximal border bisinuate 

 with a small cardelle at each side and a bifurcate lyrula in the midline, 

 deeply immersed within the peristome. On the proximal border there 

 is a moderate-sized avicularian chamber, asymmetrically located, the 

 rostrum high and lobed; a spatulate mandible; opposite this is a high 

 peristomial lappet of similar form, the two producing a large slit-like 

 sinus in the secondary aperture. 



The ovicells at first are hemispherical and prominent, about 0.40 mm 

 wide, with large pores, but with advancing calcification they become 

 almost completely immersed. 



