NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA — CHEILOSTOMATA 107 



Family Steganoporellidae Smitt, 1873 

 The zooecia are dithalamic, the cavity more or less divided by a cross- 

 wall or partition, the descending lamina of the cryptocyst, into proximal 

 and distal cavities. The horizontal lamina of the cryptocyst is complete 

 above the proximal cavity; the descending lamina perforated by the poly- 

 pide tube, which is more or less calcified, sometimes only the roof of the 

 projecting distal portion being calcified. The opesia is confined to the 

 distal cavity and is further limited to a greater or less extent by the sur- 

 rounding cryptocyst. In the genus Steganoporella there are two kinds of 

 zooecia, the "B" zooecia having an enlarged operculum provided with 

 chitinous teeth, apparently an incipient avicularium. In other genera, 

 Labioporella and Siphonoporella, there are large vicarious avicularia 

 which replace zooecia in the series. 



Genus STEGANOPORELLA Smitt, 1873 

 This genus is distinguished from others in the family by the presence 

 of two kinds of zooecia. Among the ordinary zooecia (A type) there are 

 others (B zooecia) which resemble them in most respects but which have 

 a much enlarged operculum with a heavy chitinous border beset with 

 chitinous teeth and which are undoubtedly incipient avicularia. Genotype, 

 Steganoporella (Steginoporella) legans Smitt {=Membranipora magni- 

 labris Busk). 



Steganoporella cornuta new species 

 Plate 12, figs. 3, 4, 5 and 6 



Zoarium encrusting, pale yellow, Zooecia of moderate size, 0.65 to 

 0.75 mm long by 0.40 to 0.65 mm wide, elongate-hexagonal, distinct; 

 mural rim high, especially at the distal end, moderately thick and finely 

 granulated. A salient, strong, pointed tubercle at each distal corner. 

 Cryptocyst coarsely granulated, the main lamina extending about half 

 the length of the zooecial cavity, descending gradually ; the frontal process 

 is elevated slightly and united with the roof of the polypide tube. The 

 remainder of the polypide tube is uncalcified. The frontal process is not 

 connected with the lateral walls and there is an elongated open opesiule 

 on each side symmetrically ; the process, except for its tip, is granulated 

 like the remainder of the cryptocyst, which is continued narrowly around 

 the opesia. 



The operculum is thin, with a heavy border sclerite which bears a 

 strong flange on either side a little above the point of attachment to the 

 condyles; no marginal teeth, length 0.13 mm, width 0.18 mm. 



