440 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



As Norman remarks, "This genus comes very near to Mucronella, 

 but differs in the absence of the denticle ("lyrula")." In addition, the 

 frontal slopes downward and thins out at the proximal border of the 

 aperture and there is no suggestion of the mucro which is characteristic 

 of Mucronella. Otherwise the two genera appear to agree in all details. 



Hemicyclopora polita (Norman), 1864 

 Plate 52, fig. 8 



Lepralia polita Norman, 1864:87. 

 Discopora emucronata Smitt, 1871 :1129. 

 Lepralia polita, Hincks, 1880:315. 

 Hemicyclopora polita Norman, 1894:124. 



Encrusting stones in a smooth reddish or yellowish-brown layer. The 

 zooecia are large, ranging from 0.75 to 1.00 mm long by 0.50 to 0.75 

 mm wide, very distinct with deep separating grooves; the frontal con- 

 siderably inflated, smooth (only in extreme calcification the surface is 

 minutely granulated), with 1 or 2 rows of areolar pores. The primary 

 aperture is large, 0.18 mm wide by 0.15 mm long, the sides straight for 

 a short distance and the proximal border usually quite straight; there 

 is no lyrula or at most a very slight irregularity near the middle of the 

 border. The peristome is slightly raised on the lateral and distal borders, 

 provided with 6 ( rarely 8 ) strong erect spines ; on the proximal border 

 the peristome is entirely wanting and there is no evidence of an umbonate 

 process or mucro. No avicularia. The dietellae vary from small to 

 moderately elongate. 



The ovicell is large, 0.40 to 0.45 mm wide by 0.35 to 0.40 mm long, 

 hemispherical and prominent, smooth and shining like the frontal: the 

 proximal pair of spines are fused in the proximal corners of the ovicell. 



The species was described by Norman from the Shetland Islands at 

 70-100 fms, and later recorded by him from the Hebrides and Green- 

 land, and from the Trondhjem Fjord, Norway. Smitt evidently over- 

 looked Norman's description and redescribed it from Spitsbergen as 

 Discopora emucronata. 



Point Barrow, Alaska, 18 to 26 fms, Arctic Research Laboratory, 

 Prof. G. E. MacGinitie, collector, abundant. 



