NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 97 



slightly higher, but there is no peristome and the operculum is at the 

 level of the frontal surface except at the proximal border where it 

 drops slightly below. The aperture is large, about 0.18 mm long by 

 0.20 mm wide, subquadrangular, nearly straight on the sides with the 

 proximal and distal borders slightly arcuate ; the strong cardelles situated 

 about one-third of the way from the proximal border. The operculum is 

 brownish with a heavy dark brown band continuous around the border; 

 proximally it is attached to the ectocyst but is easily separable from it. 



The avicularia are unusually large, interooecial, scattered, occupy- 

 ing a place in the zooecial series, the chamber 0.60 to 0.80 mm long by 

 0.40 to 0.50 mm wide; the dark brown mandible usually from 0.40 to 

 0.50 mm long, spatulate in form, with 3 strong unguiculate teeth at the 

 end and 2 or 3 smaller ones along the sides, somewhat resembling a 

 grappling hook ; it is broadened at the base and attached to a strong pivot. 



No ovicells, no spines. 



Type, AHF no. 25. 



Type locality, Hancock Station 1049-40, Angel de la Guardia Island, 

 Gulf of California, 29°32'47"N, 113°34'35"W. Also dredged at Sta- 

 tions 650-37, San Francisco Island and 2180, oflF IVlagdalena Bay, Gulf 

 of California; 136-34, Clarion Island, west of Mexico; 217, Tenacatita 

 Bay, Mexico; 468-35, Port Parker, Costa Rica and "off Colombia." 

 Also Albatross Sta. D.2825, Gulf of California. Shore to 50 fms. 



Family HiantOporidae MacGillivray, 1895 



In the genus Hiantopora MacGillivray, 1887, there is a pericyst 

 formed by the fusion of branching spines above the ectocyst; these often 

 form an almost complete cover, with large irregular pores. Marginal and 

 interzooecial avicularia may be present. Dorsal tubular processes are for 

 attachment. The ovicell is not closed by the operculum. 



Tremopora Ortmann, 1890 is similar in appearance to Hiantopora, 

 but the spines are less developed, the ectocyst more exposed, and the ovi- 

 cell is closed by the operculum. 



In Tremogasterina Canu, 1911, the pericyst is formed in a different 

 manner, there is no evidence of origin from spinous processes and the front 

 is solidly bridged over except for the presence of 2 or 3 large central 

 pores. The ovicell is hyperstomial and closed by the operculum. 



The first two genera are apparently closely associated, but Tremo- 

 gasterina differs so much that its position is questionable. Like the cribri- 

 morphs and the Arachnopusiidae it has an external resemblance to the 

 Ascophora, but the ectocyst extends over the opesia beneath the pericyst. 



