NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 383 



considerably wider (0.07 by 0.10 mm), straight on the proximal border. 

 The bordering sclerite of the operculum is usually dark brown. The 

 peristome is slightly salient with 5 to 7 strong spines which are some- 

 times black at the basal joint; the proximal spine on either side is occa- 

 sionally forked at the tip, as in Busk's figure (plate 31, fig. 4). The 

 ascopore has a semilunar slit and is finely dentate all around its inner 

 border, with the usual projecting shelf; it is partially surrounded 

 proximally by a semicircular umbonate process ("a pouch-like rostrum," 

 Busk) of varying height and width. The avicularia are single (Busk) 

 or paired at the side of the ascopore (rarely more proximal), with 

 setose mandibles which are directed forward and slightly outward. Busk 

 states that the mandible ("vibraculum") is black, but in our specimens 

 they are only occasionally tinged with brown. 



The ovicell is large, 0.30 mm wide, globular and prominent, its 

 surface like the frontal, ribbed around the base and in full calcification 

 the lip of the aperture is produced into a strong rib; the sides of the 

 ovicell stop abruptly at the proximal spines. 



Busk described this species from Madeira and Norman refigured 

 it from the same locality (plate 38, fig. 7). It differs from ciliata in 

 the position of the avicularia and the nature of the ooecium as well as 

 by the presence of the peculiar umbonate process. 



Hancock Stations: 155-34, Albemarle Island; 182-34 and 462, James 

 Island; 810-38, Barrington Island and 435, Chatham Island, Galapagos; 

 136-34, Clarion Island, W. of Mexico; 234, Baja Point, Lower Cali- 

 fornia. 17 to 73 fms. 



Microporella pontifica new species 

 Plate 44, fig. 5 



Distinguished by the peristome of the fertile zooecia which encloses 

 the ascopore and extends forward upon the ovicell and which is bridged 

 across near the middle to produce two secondary apertures; also by the 

 avicularium which is lateral, proximal to the ascopore and with an 

 aciculate or narrowly lanceolate mandible which is grooved on its 

 under surface. 



Encrusting on shells and corallines. The zooecia are of moderate 

 size, 0.50 to 0.60 mm long by 0.40 to 0.45 mm wide ; the frontal finely 

 granular, less inflated and the separating grooves more shallow than is 

 usual in the genus. The aperture is semicircular, 0.08 mm long by 0.10 

 mm wide, straight on the proximal border and without cardelles; the 

 peristome of infertile zooecia elevated distally and with 4 to 6 short 



