NO. 1 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 43 



The endozooecial ovicell is very shallow, inconspicuous and is formed 

 by the elevation of the distal mural rim, closed by a special membrane. 

 The position of the ooecium is rendered very conspicuous by the develop- 

 ment of a thick-walled, bilobate ooecial cover which rises from the base 

 of the succeeding zooecium. This structure resembles the ooecial cover 

 in the genus Tegella, as it does not fuse with the ovicell, but it is not 

 developed in connection with an avicularium and there is a dumb-bell- 

 shaped membranous area on the top. The infertile zooecia do not possess 

 this structure, but it appears on every ovicell. The center of the colony 

 presents an altogether different appearance from the fertile area. In the 

 infertile zooecia the operculum extends to the distal wall, but in the fer- 

 tile ones it is somewhat remote and the frontal membrane distal to it 

 appears to rise to close the ovicell. 



The M. macilenta of Jullien and Waters is merely the infertile stage 

 of nigrans. Osburn followed Nordgaard in placing nigrans in the genus 

 Callopora, but the endozooecial ovicell and the lack of pore chambers 

 preclude that association. Canu and Bassler included it under their genus 

 Adenifera, but it definitely has a small ooecium and otherwise differs 

 from Bif lustra armata Haswell, which is the genotype of Adenifera. 

 Because of the nature of the ovicell this unusual species appears to con- 

 form more nearly to the definition of the genus Hincksina. 



Hincks described the species from the Houston Stewart Channel, 

 British Columbia. Jullien's record of macilenta from north of Spain, and 

 Waters' from Wilczek Land refer to the young stage. Osburn has 

 recorded it from Etah, Greenland ; Port Burw^ell, Ungava, Canada, and 

 from the Canadian Arctic Expedition Sta. 23, 70°24'N Lat., 161°25'W 

 Long. It is doubtless another circumpolar species. 



Dall, Alaska collection, 1623-1670, one mature colony on a shell. It 

 is abundant at Point Barrow, Alaska, at 18 to 25 fms, G. E. MacGinitie, 

 collector, Alaska Research Laboratory. 



Hincksina pacifica new species 

 Plate 5, fig. 1 

 Zoaria encrusting on shells, white to light yellow in color. Zooecia 

 moderately large (0.55 to 0.80 mm long), distinct; opesia occupying 

 nearly all of the front, oval or elliptical; mural rim somewhat thickened, 

 finely beaded, the narrow descending cryptocyst similar in texture; gym- 

 nocyst vestigial. Operculum thin, semicircular, with yellow bordering 

 sclerite. Avicularia vicarious, scattered, the chamber more or less rhombic 

 in form, sides of the rostrum thin and elevated, the narrow tip often 



