344 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



The known fossil species of this genus are : 



Stephanosella (Lepralia) entomostoma Reiiss, 1847. 



Stephanosella (Lepralia) seriata Eeuss, 1874. 



Stephanosella strictifissa MacGillivray, 1895. 



The genotype Schisoporella biaparta Michelin, 1845, lives ta-day off the Azores 

 (Norman), in the waters of Florida (Smitt), and off the eastern coast of the 

 United States (Osburn). The currents have also carried the species along the 

 western coasts of the United States (Roberston). 



The simultaneous occurrence in Europe and America of Stephanosella (ScMso- 

 porella) entomostoma Eeuss, 1847, shows again that the equatorial currents were 

 already in existence in the Vicksburgian age. 



Q 



E xB 



-mf 



D -85 



FIG. 102. Genus Stephanosella Canu and Bassler, 1917. 



A-D. Stephanosella biaperta Michelin, 1845. A. Zooecia, X 30. B. Zooecia with ovicells 

 and avicularia, X 30. (After Hincks, 1880.) C. Operculum of the variety divergens. (After 

 Norman, 1903.) D. Operculum, X 85. mf, muscular insertion. 



E. Mandible, X 85. (After Nordgaard, 1906.) 



STEPHANOSELLA PARVIPORA, new species. 



Plate 85, fig. 22. 



Description. The zoariurn incrusts bryozoa. The zooecia are distinct, some- 

 what elongated, subhexagonal, irregular; the frontal is smooth, little convex, 

 bordered by widely spaced, very small areolae. The aperture is very small, -trans- 

 verse, and is provided with a wide rimule. The ovicell is large, salient, sur- 

 rounded by a collar. One or two irregular, oral avicularia are placed at dif- 

 ferent heights and deform the zooecia. 



JAa=0.04-0.045 mm. . [7,2=0.35 mm. 



Measurements. Aperture \i n -_ n nfr Zooecia , 



Ui7,=0.06-0.07mm. lfe=0.25mm. 



Affinities. The frontal of the ovicell is very fragile and does not always 

 exist on the fossils ; only the outer collar persists. 



This species differs from Stephanosella entomostoma Eeuss, 1847. in its much 

 smaller aperture (7(2=0.06 mm. instead of 0.12 mm.). Its other micrometric 

 dimensions are also much smaller than those of Stephanosella (Schizoporella) 

 biaperta Michelin, 1845. 



Occurrence. Vicksburgian (Marianna limestone) : Three miles southeast of 

 Vosburg, Jasper County, Mississippi (rare). 



Holofype.Csit. No. 64270. TJ.S.N.M. 



