304 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Tliis species is somewhat like the Cribrilina clielys Koschinsky, 1885. of the 

 Priabonian of the Vicentin. The latter, however, is provided with interzooecial 

 -avicularia. 



We unfortunate!}' possess only the figured specimen. 



Occurrence. Vicksburgian (Byram marl) : Byram. Mississippi (very rare). 



Holotype.C*t. No. 64-261, U.S.N.M. 



GEPHYROTES QUADRISERIALIS. new species. 



Plate 42, figs. 4, 5. 



Description. The zoarium is free, cylindrical, bifurcated, formed of four longi- 

 tudinal rows of zooecia opposed to each other, two by two. The zooecia are dis- 

 tinct, elongated, separated by a furrow. The frontal is very convex and formed 

 of nine pairs of closely united costules. Each costule bears at least two lumen 

 pores; the first pair bifurcates to form the spiramen and the peristomial lamella. 

 The aperture is elliptical and transverse and buried at the bottom of the peri- 

 stomice. 



. f/:.?=0.65-0.75mm. 



Measurements. Zooecia , . , 



17.2=0.40 mm. 



Affinities. The spiramen is not constant and is sometimes replaced by a pseu- 

 dorimule cut at the middle of the lower lip of the peristomice. 



As the spiramen is almost vertically placed, it is clearly visible only when the 

 specimen is inclined : then, viewing it transversely, the proximal border of the 

 aperture beneath it is quite visible. The lacunae are so small that they can not 

 be shown in the figure. 



The genus Corl>ulipoi-a of MacGillivray also has quadriserial zoaria, but the 

 zooecia have no spiramen. 



The structure of the costules is identical with that in Gcphyrotes convexa; 

 but G. quadrherii.il>* differs in its free and nanincrusting zoarium, in its nonovi- 

 celled zooecia bearing a spiramen. and in the entire absence of a zooecial gymnocyst. 



The species under discussion is the equivalent of Cribrilina crenatimargo- 

 I,, nieri Eeuss, 1847, of the Priabonian of the Vicentin, but differs from it in its 

 quadriserial and not bilamellar zoarium and in the presence of the spiramen. 



Gephyrotes quadriserialis furthermore has no oral avicularia and is of such 

 an aberrant type that it will be convenient perhaps to separate it generically when 

 the ovicell has been discovered. 



Occurrence. Upper Jacksonian (Ocala limestone) : Chipola River, east of 

 Marianna, Jackson County, Florida (rare). 



Cotypes.CsA. No. 64031, U.S.N.M. 



Genus METRACOLPOSA Canu and Bassler, 1917. 



1917. Metracolposa CANU and BASSLER, Synopsis of American Early Tertiary Cheilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 34. 



The costules are separated by numerous lacunae. The aperture is semilunar. 

 The operculum in opening closes the ovicell. The ovicell is large and deeply em- 

 bedded in the distal zooecia. The ovicelled zooecia have a large aperture. 



