NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 341 



rather large suboral avicularium occupies the triangular area proximal 

 to the aperture, the mandible semicircular to short subspatulate and 

 hinged to a complete bar, sometimes inclined forward toward the aper- 

 ture but usually nearly level with the frontal surface, often wanting. 

 The avicularian chamber is symmetrically developed in the median line 

 but does not connect with marginal pores. 



The ovicell is hyperstomial but considerably embedded in the distal 

 zooecium and closed by the operculum, perforated in a rather regular 

 pattern, 0.20 to 0.24 mm wide. 



It is an arctic and high northern species, known from Nova Zembla 

 to Greenland and down the Atlantic coast of North America to Maine. 

 In the Canadian Arctic Expedition it was found at Icy Cape and Point 

 Barrow, Alaska (Osburn, 1923:10, Smittina reticulato-punctata) . It is 

 possible that the Smittia Landsborovii var. porifera of O'Donoghue 

 (1923:42) from British Columbia, also belongs here. 



Bering Sea (Dall Collection, United States National Museum). 

 Common at Point Barrow, Alaska, G. E. MacGinitie, collector. 



Hippodiplosia insculpta (Hincks), 1882 

 Plate 40, figs. 1-2 



Schizoporella insculpta Hincks, 1882:252. 

 Schizoporella insculpta, Robertson, 1900:326; 1908:290. 

 Schizoporella insculpta, O^'Donoghvit, 1923:36; 1925:102; 1926:57. 



Zoarium encrusting on almost anything that will afford attachment, 

 stones, shells, hydroids, bryozoans, algae, etc., often rising in short 

 bilaminate frills or fan-like expansions; light yellow, but bright orange 

 when in reproduction. Zooecia elongate-quadrangular to more or less 

 hexagonal; length 0.50 to 0.75 mm, width 0.30 to 0.40 mm; distinct 

 and a little inflated. Front a tremocyst, slightly granular, with numerous 

 large pores; there is a pointed umbo, with its base about as wide as the 

 aperture and a crescentic cavity on its distal side is sometimes partially 

 closed to form a rounded pore, but no evidence of an avicularium has 

 been found. The peristome is low and very thin, not covered by the tremo- 

 cyst. The aperture is round back to the strong cardelles; proximal to 

 these is a broad, shallow poster with a slightly arcuate border; in the 

 infertile zooecia the aperture measures 0.18 to 0.20 mm in each dimen- 

 sion, in the fertile zooecia the aperture is larger but of the same form. 

 The operculum is thin, without any marked sclerites and the muscle 

 attachments are well removed from the border; in the fertile zooecia it 

 is larger and closes the ovicell. 



