106 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Rosseliana rosselii (Audouin), 1826 



Membranipora rosselii, Hi'ncks, 1884:7. 



"Houston-Stewart Channel, British Columbia, on shells, not uncom- 

 mon," Hincks. The species has not been found on the Pacific coast since, 

 nor has it been reported from any areas except the Mediterranean and 

 western Europe. 



Genus MIGROPORINA Levinsen, 1909 



Erect colonies, often branching profusely to a height of several inches ; 

 jointed, the internodes terete, tapered at the proximal end and rounded 

 at the tip. Zooecia with the cryptocyst filling the frontal area nearly to 

 the aperture which is almost semicircular; in younger stages small opesi- 

 ules may be seen but these are usually closed by later calcification. A small 

 avicularium occurs just distal to the aperture. No spines. No ovicells. 

 Genotype, Salicornaria borealis Busk, 1855. 



Microporina borealis (Busk), 1855 

 Plate 11, fig. 2 



Cellaria borealis, Robertson, 1900:322; 1905:287. 

 Cellaria borealis, O'Donoghue, 1923 :23. 

 Microporina borealis, O'Donoghue, 1926:49. 



Zoarium erect and branching, often in luxuriant growth several inches 

 in height; the rounded internodes averaging about 1 cm in length, the 

 joints chitinous. The zooecia are moderately large, about 0.75 mm long 

 by 0.30 mm wide, arranged in 12 to 16 rows around the internode, 

 alternating regularly so that they appear to form spiral as well as longi- 

 tudinal series. The margins are little raised, more so about the distal end. 

 The front, beneath the ectocyst, is a flat porous cryptocyst which fills 

 the whole front almost to the operculum. The aperture is nearly semi- 

 circular, slightly rounded on the proximal border. Distal to the aperture 

 and in line with it is a small avicularium with the triangular mandible 

 directed proximally. There are no ovicells. 



It is a northern species abundant in Greenland waters, but ranges 

 south on the Pacific coast from Bering Sea to British Columbia (Robert- 

 son and O'Donoghue). 



A couple of small fragments occurred in the Dall collection labeled 

 only "Bering Sea." Also at Point Barrow, Alaska, 14 fms, G. E. Mac- 

 Ginitie, collector, Alaska Research Laboratory. 



