NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 503 



areolar pores and scattered frontal pores, the form of the primary aper- 

 ture and the nature of the operculum, the complete ovicell, and frontal 

 and oral avicularia. The oral spinous processes are wanting in porosa 

 Canu and Bassler and little developed in pertusa Smitt. Suboral avicu- 

 laria are often wanting in all of the species and rare in porosa and 

 hexago7ialis. 



Trematooecia porosa (Canu and Bassler), 1930 

 Plate 60, figs. 8-9 



Holoporella porosa Canu and Bassler, 1930:39. 



The zoaria form small rounded or cap-like encrustations on coralline 

 nodules, etc. The zooecia are perfectly erect, even at the growing edge, 

 the exposed ends roughly hexagonal, averaging about 0.40 to 0.45 mm 

 in diameter; somewhat swollen, a row of areolar pores and one or two 

 rows of smaller ones which are carried upward toward the aperture in 

 secondary calcification. The primary peristome is low and thin and soon 

 becomes obscured by the encroachment of the heavy frontal wall. The 

 aperture is large, 0.20 mm long by 0.18 mm wide, rounded in front, 

 the proximal border somewhat arcuate, the widest part immediately 

 proximal to the heavy cardelles ; it is situated near the middle of the 

 frontal area and one or two rows of pores surround it distally. Rarely 

 a minute suboral avicularium is present, either median or at one side 

 of the midline. Minute rounded avicularia are also occasionally present 

 on the front. 



The ovicell is large, about 0.45 mm wide, hemispherical, the aper- 

 ture not wide open, the primary cover perforated with small pores, which 

 become obscured as the secondary layer advances over it. There are no 

 oral spines or prominences. 



Canu and Bassler described the species from the Galapagos Islands, 

 Albatross D.2815, a single specimen. 



Hancock Stations: 276, San Esteban Island, Gulf of California, 

 28°38'30"N, 112°36'00''W, 32 fms; and at 440, 441 and 442, 20 to 

 24 fms, and 452, Charles Island, 65 fms, Galapagos. 



Trematooecia hexagonalis (Canu and Bassler), 1930 

 Plate 60, fig. 7 



Holoporella hexagonalis Canu and Bassler, 1930:38. 



Encrusting shells, corallines, worm tubes, etc., sometimes multi- 

 laminar. The zooecia are erect. The measurements, the porosity of the 

 frontal, the nature of the aperture (except that the cardelles are smaller 



