350 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Hippoporella hippopus (Smitt), 1867 

 Plate 45, figs. 8-9 



Lepralia hippopus Smitt, 1867:20, 

 Lepralia hippopus, Hincks, 1880:309. 

 Lepraliella hippopus, Levinsen, 1916:466. 

 Hippoponella hippopus, Osburn, 1933:44. 



The zoarium is encrusting on stones and shells, vitreous or white 

 and glistening. The aperture is round anteriorly, nearly straight on the 

 sides, the proximal border only slightly arcuate; 0.15 mm long by 0.12 

 mm wide ; the strong cardelles are set far back and the shallow poster 

 is about as broad as the anter. The vestibular arch smooth or delicately 

 beaded. The operculum fills the aperture, well chitinized and yellow in 

 color, indented on the sides at the position of the cardelles, and with a 

 slightly sinuous sclerite separated from the border. The peristome is low 

 and thin, with 2 to 4 small spines which soon disappear. The avicularia 

 are round or ovate and vary in size, usually small, often one is found 

 situated at one side of the median line and proximal to the aperture; 

 others may apparently occur at any other position on the front. 



The ovicell is hyperstomial, not closed by the operculum, hemi- 

 spherical, imperforate and smooth ; it soon becomes more or less com- 

 pletely immersed. 



This species has a slightly longer aperture and a smoother frontal 

 than our other species ; while the frontal becomes more coarsely granu- 

 lated and irregular it never seems to develop the heavy tuberosities which 

 are found on nitescens and gorgonensis. It has been recorded in Arctic 

 waters from Spitsbergen to Greenland and the American Archipelago, 

 and in the North Atlantic south to Great Britain and to Maine on the 

 New England coast. 



Point Barrow, Alaska, Arctic Research Laboratory, 6 fms, common, 

 G. E. MacGinitie, collector. 



Hippoporella nitescens (Hincks), 1884 

 Plate 45, figs. 4-5 



Lepralia nitescens Hincks, 1883 : 450. 

 Lepralia nitescens, O'Donoghue, 1923 :40. 

 Hippoporella nitescens, Hastings, 1930: 724. 



The zoarium encrusts pebbles, shells, etc. The zooecia are of moderate 

 size, 0.45 to 0.65 mm long by 0.40 to 0.50 mm wide, irregularly ovate, 

 quincuncial, considerably inflated, distinct in younger stages. The frontal 

 is a very thick vitreous or porcellanous pleurocyst, with a marginal row 



