174 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.14 



the Ascophora. Certainly such typical cribrimorphs as Cribrilina, Lyrula 

 and Reginella with a large costal area above a broad frontal membrane 

 cannot properly be included in the Ascophora. 



The family Cribrilinidae includes practically all of the recent genera. 



Family Gribrilinidae Hincks, 1880 



Key to the Genera of Cribrilinidae 



1. No ooecia, no dietellae, avicularium large, vicarious, spatulate. 



Lyrula 



Ooecia present, hyperstomial ; avicularia not spatulate 2 



2. Avicularia present 3 



Avicularia w^anting (in the species here considered) 4 



3. Avicularia vicarious or pedunculate at side of aperture . Colletosia 

 Avicularia minute, mandible setose Puellina 



4. Costules separated for most of their length. . . Membraniporella 

 Costules more or less fused for their entire length 5 



5. Costate area reduced, costae closely united, no dietellae, gymno- 



cyst well developed Figularia 



Costate area covering nearly the whole front 6 



6. Ooecia large, prominent, no dietellae Reginella 



Ooecia small, not prominent, dietellae present. . . . Cribrilina 



Genus MEMBRANIPORELLA Smitt, 1873 



The frontal membrane is overarched by a series of costules which are 

 free from each other for much of their length, but more or less fused at 

 their tips ; the distal pair forming the proximal lip of the aperture. Paired 

 avicularia may occur at the sides of the aperture, but are not found in 

 our species. The ovicell is hyperstomial. Dietellae present or wanting. 

 Genotype, Lepralia nitida Johnston, 1847:319. 



Membraniporella aragoi var. pacijfica new variety 

 Plate 27, figs. 3 and 4 



Encrusting, especially on shells. It has all the appearance of a mem- 

 branipore with an arched lattice-work above the frontal membrane. The 

 zooecia are moderate in size, but show much variation, 0.40 to 0.65 mm 

 long by 0.30 to 0.40 mm wide. The frontal shield or pericyst is formed 

 by the fusion of the branched tips of large, flattened, hollow spines which 

 arise on the mural rim, curve over the frontal membrane and interlock, 

 leaving usually 6 or 8 more or less ellipsoid lacunae in the central area. 

 The usual complement of the spines or costulae is 4 on each side, but 

 there may be as few as 3 or as many as 6 in the same zoarium ; frequently 

 there is a single median costa proximally; the costae are separated at 



