310 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Posterula sarsi (Smitt), 1867 

 Plate 35, fig. 6 



Escharoides sarsii Smitt, 1867 :24. 

 Posterula sarsi, Jullien, 1903:98. 

 Escharoides sarsi, Robertson, 1908:301. 



Zoarium with encrusting base, rising in coarse, bilaminate branches 

 or frills to a height of 100 mm or more; often only the encrusting base 

 is present and this may spread over wide areas of shells and stones. 

 Zooecia large with very variable measurements, 0.60 to more than 1.00 

 mm long by 0.45 to 0.60 mm wide; smooth and somewhat swollen in 

 younger stages; a marginal row of ovate pores with short costae be- 

 tween; the frontal wall soon becomes very thick and roughened. 



The primary aperture is oval, but varying considerably in form, 

 without sinus or cardelles. The secondary aperture is irregularly pyri- 

 form with a deep, irregular sinus, with one or more pointed, oval or 

 rounded avicularia submerged within the sinus; the avicularia may pre- 

 sent the following variations; one in the middle or at one side, one on 

 each side, one in or near the middle and one on each side, or as many 

 as four have been noted, all situated below the level of the frontal crust. 

 No spines. 



Robertson first recorded from the Pacific area this well-known Arctic 

 species, "A large colony growing over a clamshell obtained at Juneau," 

 Alaska. 



A large frilled specimen was taken at Hallo Bay, Alaska, by the 

 U. S. Alaska Crab Investigation, 40-28 fms. Also common at Point 

 Barrow, Alaska, Arctic Research Laboratory, G. E. MacGinitie, col- 

 lector. 



Genus RAGIONULA Canu and Bassler, 1927 



Formerly assigned to Eschara, Escharopsis, Discopora and Escha- 

 roides, until Canu and Bassler very properly erected a new genus for it. 



"The ovicell is hyperstomial, opening into the peristomie, not closed 

 by the operculum. The frontal is (in appearance) a very thick, granular 

 pleurocyst. The aperture is semicircular. The peristomice bears a pseu- 

 dorimule bordered by a small eccentric peristomial avicularium. The 

 operculum and the mandible are of the type of Porella." (Canu and 

 Bassler, 1930:294.) Genotype, Eschara rosacea Busk, 1856:33. 



