396 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



laterally on both sides to the marginal areolae, and is perforated by a 

 varying number of pores, usually 2 to 6 (the areolar pores of the keno- 

 zooecium) ; the rostrum is elevated, directed slightly over the aperture 

 and bears a small avicularium with a semicircular or slightly triangular 

 mandible. Additional small avicularia are usually present on most of 

 the zooecia. Hincks figured them in several positions (Plate 4, fig. 4), 

 most frequently 1 or 2 near the proximal end of the frontal, but often 

 there are several ; occasionally they are wanting on most of the zooecia. 



The ovicell is prominent, round and smooth, 0.16 to 0.18 mm in 

 width, the peristome forming a thin lip above the orifice ; in very advanced 

 calcification the ovicells may become completely immersed. 



Hincks described it from the Queen Charlotte Island and O'Don- 

 oghue listed it from a number of British Columbia localities. Canu and 

 Bassler recorded it from the Pleistocene of Santa Monica, California. 

 The latter authors also described the form with numerous avicularia as 

 Cystisella aviculifera from the same locality, placing it in that genus 

 because of the absence of lateral areolar pores. However, younger zooecia 

 always show the areolar pores quite distinctly when calcined, small and 

 widely separated with no evidence of costal ridges. It is very probable 

 that the pores of the type material had become occluded with age or 

 fossilization. At any rate it could not remain in the genus Cystisella in 

 which the avicularian chamber rises in connection with the proximal 

 areolar pores and extends the full length of the frontal. 



Hancock Stations: dredged at numerous stations from the Oregon 

 coast south to Cedros and the San Benito Islands off Lower California, 

 the most southern record at Station 309, Port Culebra, Costa Rica; 

 most abundant about the islands off southern California; 6 to 100 fms. 



Porellaconcinna (Busk), 1854 

 Plate 46, figs. S-6 



Lepralia concinna Busk, 1854 :67. 

 Porella concinna, Hincks, 1884:24. 

 Porella concinna, Robertson, 1908 :300. 

 Porella concinna, O'Donoghue, 1923 :40. 



Zoarium encrusting on shells and stones. The zooecia are of moderate 

 size, averaging about 0.50 mm long by 0.35 mm wide, distinct when 

 young but tending to become immersed in a heavy crust. The frontal is a 

 pleurocyst, shining but somewhat rough in the young stage and becoming 

 rougher and very thick with increasing calcification. The areolar pores 

 are few in number and in older specimens may become completely 



