18 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



The zooecia occur in pairs, back to back, and branches arise from the 

 sides of the zooecia near the distal end. The proximal end of the zooecium 

 is tubular and gradually expanding, the opesia occupies about half the 

 zooecial length and slopes downward to the distal rim. There are no 

 ovicells, spines nor avicularia. The zoaria form bushy colonies sometimes 

 nearly 100 mm in height, of a light yellowish color. 



It is circumpolar in distribution and ranges down the Atlantic coasts 

 of Europe to France and to Cape Cod in North America. On the Pacific 

 coast it extends to southern British Columbia. Furthermore, Marcus 

 ( 1937 :31 ) has taken it at Santos, Brazil, the only positive record for the 

 southern hemisphere, and Norman (1909:238) reported it questionably 

 from Madeira. 



Hincks and O'Donoghue listed it from a number of localities in 

 British Columbia, Robertson from Prince William Sound and Juneau, 

 Alaska, and Osburn (1923) from Point Barrow, Alaska. 



In the Hancock collections there are specimens from Kodiak, the 

 Pribilof Islands and Point Barrow, Alaska. 



Family Membraniporidae Busk, 1854 



There has been much dispute in regard to this family and it is difficult 

 to draw a diagnosis. In general the simplicity of its members is the most 

 striking character. The opesia is nearly as large as the zooecial front and 

 the frontal membrane covers the whole surface ; the gj^mnocyst is want- 

 ing or much reduced except in Desmacystis; the cryptocyst varies from 

 scarcely discernible to filling half of the opesia; ovicells are entirely 

 wanting; avicularia are wanting in most of the species, but incipient 

 vicarious avicularia, little modified and as large as the zooecia, are found 

 in a few species; in Desmacystis there is a median frontal avicularium, 

 and in Cupuladria there are highly specialized vibracula. Mural spines 

 are wanting, but tubular processes or low tubercles may be present at the 

 distal corners. 



Key TO THE Genera of Membraniporidae 



1 . Zoarium free, cupuliform, long vibracula present. . . Cupuladria 

 Zoarium attached, encrusting or erect 2 



2. Gjnnnocyst covering proximal half of zooecium, a median avicu- 



larium proximal to the opesia Desmacystis 



Gymnocyst wanting or little developed 3 



3. Triangular open areas, or triangular or rounded knobs on the 



basal corners, developed on a small g}'mnocyst. . . Conopeum 



