NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 65 



Gallopora aurita (Hincks), 1877 

 Plate 7, fig. 2 



Membranipora aurita Hincks, 1877 ;213. 

 Membranipora aurita, Oshurn, 1912:230; 1933:21. 



Zoarium encrusting, usually on shells, forming very regular rounded 

 colonies when not crowded. Zooecia moderate in size, ovate, considerably 

 narrowed toward the distal end ; walls high and strongly calcified ; in 

 older stages the cryptocyst forms a narrow shelf; gymnocyst occupying 

 about one-fourth of the zooecial length. Usually with a single erect 

 spine just proximal to the operculum on one or both sides, occasionally 

 an additional smaller spine is present. Avicularia: when an ovicell is 

 present there is a pair of small avicularia on the gj^mnocyst, directed 

 forward and outward ; in the absence of an ovicell there is a single larger 

 avicularium with its mandible directed backward. 



The ovicell is rounded, more or less immersed, with a strong raised 

 rib which encloses a triangular area above the orifice and which may rise 

 to form an umbo on the top. 



This is a common species on both sides of the North Atlantic but its 

 presence in the Pa'cific has not hitherto been noted. 



Canoe Bay, Alaska, 125 fms, U. S. Alaska Crab Investigation, Sta. 

 24-40. Also at Point Barrow, Alaska, Arctic Research Laboratory, G. E. 

 MacGinitie, collector. 



Gallopora circumclathrata (Hincks), 1881 

 Plate 8, fig. 2 

 Membranipora circumclathrata Hincks, 1881 :131. 

 Membranipora circumclathrataj Kohertson, 1908:259. 

 Membranipora circumclathrata, O'Donoghue, 1923 :24. 

 Gallopora circumclathrata, O'Donoghue, 1926:33. 

 Gallopora circumclathrata, Canu and Bassler, 1923:43. 

 Retevirgula circumclathrata. Brown, 1948:110. 



Zoarium encrusting on shells, stones and algae, but loosely attached. 

 Zooecia about 0.50 mm long by 0.30 mm wide, well separated by deep 

 grooves, or disjunct and united by short tubules with small fenestrae 

 between them; walls moderately thick; mural rim smooth or slightly 

 granular, the descending cryptocyst somewhat crenulate on its inner 

 border; gymnocyst well developed, frequently covering one-third of the 

 zooecial front; opesia oval to elliptical. Spines: one or two distal pairs 

 more or less erect ; three to five on each side, much flattened and bending 

 strongly across the opesia, their points often touching. 



