NO. 1 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 41 



Avicularia not paired, or if paired they are on the lateral walls; 



cryptocyst less developed 4 



4. Avicularia large, or paired on the lateral walls ; ovicells small 



but evident on the surface Hincksina 



Avicularia single at distal ends of zooecia, ovicells not evident 



on the surface 5 



5. Mandible very long and winged Cranosina 



Mandible short, pointed, not winged Ellisina 



Genus HINCKSINA Norman, 1903 

 Zooecia encrusting, entire area membranous, mural rim with or with- 

 out spines. Ovicell endozooecial, occasionally conspicuous but usually 

 small, short and sometimes scarcely evident. No dietellae. Avicularia usu- 

 ally interzooecial. Genotype, Membrwiipora flustroides Hincks, 1880. 



Key to Species of Hincksina 



1. Avicularian mandible very elongate 2 



Mandible not extremely elongate 4 



2. Mandible setiform and winged on both sides alba 



Mandible not winged 3 



3. With numerous spines bending over the opesia pallida 



Spines wanting pacifica 



4. Avicularia lateral and paired nigrans 



Avicularia not lateral and not paired 5 



5. Mandible triangular, usually with one side longer than the other. 



velata 



Mandible semicircular 6 



6. Numerous spines bending low over the opesia. . . . polacantha 

 No spines minuscula 



Hincksina alba (O'Donoghue), 1923 

 Plate 5, fig. 2 



{Membranipora alba), 0'T)onog\\\xe, 1923:28. 

 Callopora alba, O'Donoghue, 1926:34. 



Encrusting, white to light yellow. Zooecia large, 0.75 to 1.08 mm 

 long by 0.40 to 0.55 mm wide; walls high, rather thick and conspicuously 

 elevated on the distal border ; opesia oval and occupying nearly all of the 

 frontal surface, 0.55 to 0.65 mm long; gymnocyst small; cryptocyst 

 limited to the border of the opesia, granular and minutely crenate at its 

 lower edge. The operculum is large, about 0.20 mm in either dimension, 

 with a conspicuous yellow bordering sclerite. 



The avicularium is vicarious, taking a place in the zooecial series, and 

 has the appearance of a symmetrical onychocellarium ; it is nearly as long 



