NO. 2 osburn: eastern pacific bryozoa — cheilostomata 279 



Hippothoa expansa Dawson, 1859 

 Plate 30, fig. 9 



Hippothoa expanse Dawson, 1859 :255. 



Hippothoa divaricata var. expansa, Verrill, 1885 :232. 



Hippothoa expansa, Hincks, 1880:291. 



This species resembles H. divaricata, but is much larger, has a cal- 

 careous lamina expanding from the dorsal sides of the zooecial body and 

 tubular portion, and the ovicell is broader than long. 



Apparently this species has not been recorded previously for the 

 Pacific coast of America. It is well distributed in the northern North 

 Atlantic and Arctic Oceans. 



Hancock Station 1283-41, Santa Rosa Island, off the coast of south- 

 ern California, 28 fms ; Palos Verdes, California, on kelp hold-fast (R. C. 

 Osburn). Common at Point Barrow, Alaska, G. E. MacGinitie col- 

 lector, Alaska Research Laboratory. 



Genus GHORIZOPORA Hincks, 1880 



"Zooecia more or less distant, connected by a tubular network; the 

 orifice semicircular, with the inferior margin entire" (Hincks, 1880:222). 

 Genotype Flustra Brogniartii Audouin, 1826. 



The genus is similar in appearance to Hippothoa hyalina, but is 

 readily distinguished by the semicircular aperture and by the presence 

 of a small avicularium distal to each zooecium and to the ooecium when 

 it is present. 



Ghorizopora brogniarti (Audouin), 1826 



Lepralia Brogniarti, Busk, 1854:65. 

 Chorizopora Brogniarti, Hincks, 1880:224. 

 Ghorizopora brogniarti, Canu and Bassler, 1930 :14. 



Zoarium encrusting in a thin layer, resembling younger stages of 

 Hippothoa hyalina in its cross-ribbed, disassociated, terete zooecia. The 

 frontal is imperforate, the only decoration being a low, pointed umbonate 

 process which overhangs the aperture ; the latter is semicircular, broader 

 than long and straight on its proximal border. At the distal end of each 

 zooecium is a small avicularium with a triangular mandible directed 

 forward. The ovicell is rounded, conspicuous, with a longitudinal carina, 

 and its distal end is surmounted by an avicularium similar to those 

 associated with the infertile zooecia. 



