NO. 2 OSBURNT: eastern pacific BRYOZOA CHEILOSTOMATA 357 



Hippoporidra granulosa Canu and Bassler, 1929 

 Plate 42, figs. 12-14 



Zoarium encrusting shells. Zooecia of the primary layer recumbent 

 and oriented, those of the secondary layers more or less erect and irregu- 

 lar, the surface roughened. The frontal is imperforate except for a row 

 of areolar pores, with rarely a few others; these pores are not carried 

 up around the base of the peristome in secondary calcification. The 

 frontal is coarsely granular even in the young stage and becomes 

 excessively thick, as thick as the cavity beneath it, the areolar pores 

 outlining the margin. The peristome is somewhat elevated in young 

 zooecia and bears six small spines which soon disappear, and the 

 thickening of the frontal soon obscures all evidence of the primary 

 peristome. The secondary aperture is oval and somewhat expanded. 

 The primary aperture is elongate, 0.14 by 0.10 mm, with strong car- 

 delles, proximal to which the semicircular sinus measures about 0.07 mm 

 across. The operculum is deeply incised on the sides at the point of attach- 

 ment and bears a strongly sinuated sclerite on each side well removed 

 from the margin. There are small frontal avicularia which appear to 

 have no special relation to the aperture. 



The ovicells are small, opening well above the primary aperture and 

 apparently have a small rounded frontal area, but in our specimen 

 they are so deeply embedded in the thick crust that details cannot be 

 determined. 



The species was described by Canu and Bassler from the Galapagos 

 Islands, Albatross Sta. D.2813. 



Hancock Stations: 1049-40, Angel de la Guardia Island, Gulf of 

 California, 29°32'47''N, 113°34'35"W, 54 fms, one colony, and 438, 

 Chatham Island, Galapagos, 32 fms, one colony. 



Genus GEMELLIPORINA Bassler, 1936 



"Proposed for species with keyhole-like aperture, hyperstomial ovi- 

 cell and tremocystal frontal, with Gemellipora glabra Smitt, 1873, a 

 common species in the Gulf of Mexico, as the type" (Bassler, 1936:161). 



The frontal is not a tremocyst, however, as young zooecia at the 

 growing edge definitely show the development of a pleurocyst with one 

 or two rows of areolar pores. On the very thick front of older zooecia 

 these pores are more or less dispersed, giving an appearance somewhat 

 like a tremocyst. The genotype has an erect zoarium with dichotomous 



