NO. 3 OSBURN : EASTERN PACIFIC BRYOZOA CYCLOSTOMATA 703 



The brood-chamber covers the central area, with a thin calcareous 

 layer which is very minutely perforated ; a coarsely reticulated layer of 

 secondary cancelli later may cover it. The ooeciostome appears to be 

 unique in this genus; it has the short erect cylindrical base but the 

 orifice is on the side, with a peculiar "helmet" or hood-shaped cover 

 which arches widely over the top, closing the orifice entirely from above ; 

 also just inside from the rim of the hood there is a transverse row of 

 minute pores, as described by Ridley under L. grignonensis (=L. ca- 

 naliculata) . 



This species has been recorded only for Antarctic and far southern 

 waters ; Kerguelen Island ; Strait of Magellan ; Kap Adare, Victoria 

 Land; and New South Wales. It is therefore of special interest to 

 discover it in the Arctic region. The nature of the tubules and especially 

 the form of the ooeciostome with its row of perforations seem sufficient 

 for positive identification. 



Point Barrow, Alaska, Arctic Research Laboratory, 110 to 522 feet, 

 several colonies, only one of which is mature, G. E. MacGinitie, col- 

 lector. 



Lichenopora verrucaria (Fabricius), 1780 

 Plate 74, fig. 3 



Madrepore verrucaria Fabricius, 1780:430. 

 Discoporella verrucaria, Busk, 1875:31. 

 Lichenopora verrucaria, Hincks, 1880:478; 1884:207. 

 Lichenopora verrucaria, Robertson, 1900:329; 1910:263. 

 Lichenopora verrucaria, O'Donoghue, 1923:15; 1926:28. 

 Lichenopora verrucaria, Canu and Bassler, 1923:205. 



Zoaria small, rarely more than 3 mm in width; encrusting on algae, 

 stems, stones and shells ; high near the center and rounding off gradually 

 to the margin where there is a narrow basal lamina. In younger colonies 

 there is a depressed cancellous central area, but in the sexually mature 

 this area is filled in with one or more brood-chambers. The zooecia are 

 irregularly arranged, often in short radiating series, especially near the 

 central area, but never connate ; moderately elevated, carinated on the 

 side toward the center, the keel rising into a point. The cancelli vary 

 greatly in size, sometimes larger than the zooecial apertures but often 

 not half as large. 



Usually only one brood chamber fills the central area, but as many 

 as three have been observed, in which case they fuse externally so that 

 the number of ooeciostomes is the only obvious clue to the number of 



