778 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



There is a narrow vestibular arch. The primary peristome is low and 

 thin and becomes covered on the sides by the encroachment of the frontal 

 wall, which modifies the form of the aperture only slightly. 



The ovicell is hyperstomial, considerably depressed and is closed by 

 the operculum; secondary calcification from the three adjacent distal 

 zooecia produces three sutural lines on the surface, and often there is 

 a pore or fenestra at the central junction of the sutures, width 0.26 to 

 0.30 mm. 



The species was described from the Kara Sea and later recorded from 

 northeast Greenland (Levinsen) and the North American Archipelago 

 (Nordgaard). 



Point Barrow, Alaska, Arctic Research Laboratory, 217 to 522 feet, 

 G. E. MacGinitie, collector, rather common. 



Hippodiplosia cancellata (Smitt), 1867 



Plate 81, fig. 6 



Escharella porifera forma cancellata Smitt, 1867:9. 

 Smittina cancellata, Nordgaard, 1906:29. 



Apparently this species has not been seen since Smitt described it. 

 Nordgaard placed it under Smittina, but without having seen it. 



The zoarium is encrusting, spreading over shells, reddish-brown in 

 color. The zooecia are moderately large, 0.65 to 1.0 mm long by 0.40 

 to 0.65 mm wide; the front a tremocyst with large pores which enlarge 

 upward until the surface is coarsely cancellous or tessellated, with only 

 narrow rims separating the pores. The only exception to this is the 

 smoother area proximal to the aperture which is characteristic of the 

 genus and upon which the secondary layer does not encroach. The aper- 

 ture is large, 0.18 to 0.20 mm wide, usually a little wider than long, 

 evenly rounded back to the small cardelles ; the proximal border broadly 

 arcuate, nearly straight, or often arched forward slightly above the 

 operculum (this last feature gives the aperture somewhat the appearance 

 of a Smittina, but it does not appear to be homologous with the lyrula 

 of the Smittinidae). Smitt described the species "Avicularia desunt," 

 but small avicularia are frequently present (though often wanting over 

 large areas), with a rounded mandible and located close to the aperture 

 in the middle on the preoral smooth area. There are no spines or other 

 surface structures. 



The ovicells are large, about 0.40 mm wide, hemispherical, hyper- 

 stomial but rather deeply embedded, smooth at first but soon becoming 

 covered with a cancellous layer similar to that of the frontal. 



