312 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



limited laterally by two peristomial avicularia more or less salient and 

 more or less visible. On the frontal a large spatulated avicularium 

 sometimes appears" (Canu and Bassler, 1929:293). Genotype, Myrio- 

 zoum marionense Busk, 1884:171. 



It should be noted that the above description of the genus was drawn, 

 as far as the ovicell, spatulate avicularium and aperture are concerned, 

 from M. marioncTise Calvet, 1903:130, which is probably a different 

 species from marionense Busk. 



Diatosula californica new species 

 Plate 35, figs. 4-5 



The zooecium is erect, rigid, rising to a height of 40 mm, branching 

 irregularly at nearly right angles, the branches of nearly uniform width 

 of about 1.30 mm, white or pale yellow in color. The zooecia are of 

 moderate size, 0.45 to 0.55 mm long by 0.30 to 0.40 mm wide; young 

 individuals distinct; the front is a smooth pleurocyst, considerably in- 

 flated, with a row of areolar pores between which are short costae; a 

 few other pores perforate the frontal, apparently without any special 

 arrangement. The distal end of the zooecium is somewhat elevated. 

 The primary aperture is a little elongate, about 0.16 mm long by 0.12 

 mm wide ; rounded at the distal end, straight and slightly converging on 

 the sides to the cardelles; proximal to these is a shallow, wide poster 

 with a small, narrow, somewhat v-shaped sinus. The operculum is bright 

 yellow, with a strong sclerite inside of the border. 



The peristome soon rises above the aperture, often bearing on each 

 side a minute rounded avicularium with a semicircular mandible, and 

 the form of the secondary aperture becomes more or less oval with a 

 proximal notch. The heavy secondary calcification soon obscures all of 

 the structural details, except near the growing tips. Large spatulate 

 interzooecial avicularia occur infrequently; these are about the size of 

 the primary aperture, oriented proximally. 



The ovicells are large, 0.26 mm wide by 0.20 mm long, hyperstomial 

 but deeply embedded and eventually may be completely enveloped in the 

 thick crust. The frontal area of the ovicell is broadly semicircular, sur- 

 rounded by a row of pores and the surface radiately striated. The sec- 

 ondary aperture of the ovicelled zooecia is strikingly different in form, 

 transversely oval and without a sinus in the proximal border. 



This species differs from D. (Myriozoum) marionense Busk (from 

 the southern Indian Ocean) in the details of the front, the shorter peri- 

 stome and in the nearly sessile oral avicularia; Busk did not mention 



