NORTH AMERICAN EARLY TERTIARY BRYOZOA. 357 



SCHIZOMAVELLA ELONGATA, new species. 

 Plnte 46, fig. 17. 



Description. The zoarium is free, formed of two lamellae, back to back and 

 inseparable; the zooecia are distinct, very elongated, fusiform, separated by an 

 improminent thread; the frontal is flat and ornamented with small, wide open 

 tremopores. The aperture is suborbicular ; the rimule is very wide, concave, scarcely 

 distinct from the anter. The ovicell is globular and salient, ornamented with a 

 tremocyst analogous to that of the frontal. The median avicularium is small. 

 triangular, without salient beak and imbedded in a cavity. 



=.ni. [7.3=1.10 mm. 



Measurements. Aperture { 7 Zooecmm , 



[7a=0.10mm. l?3=0.30mm. 



Affinities. This species is characterized by its very great zooecial length. We 

 have observed two cnlcified zooecia ; the aperture is covered by the tremocyst and 

 replaced by a small pore. The physiologic role of such zooecia is unknown to us. 



Occurrence. Middle Jacksonian : Three and one-half miles north of Grovania, 

 Georgia (rare). 



ftolotype.C&t. No. 64060. U.S.N.M. 



SCHIZOMAVELLA ARBOREA, new species. 



Plate S6, figs. 1-G. 



Description. The zoarium is free, arborescent, rectangular, or cylindrical. 

 The zooecia are disposed in four longitudinal rows, alternating and placed back 

 to back; they are hexagonal, very little elongated, separated by a prominent thread. 

 The frontal is a direct tremocyst with large pores. The aperture is small, oblique 

 and formed of a semilunar anter and of a very wide rimule of little depth. The 

 ovicell is large, globular, salient, punctate; it is closed by the zooecial operculum 

 which is larger on the ovicelled zooecia. The median avicularium is elliptical, 

 salient, separated into two parts by a wide pivot. 



[A#=0.10mm. . fZ2=0.80mm. 



Measurements. Aperture { , . . n Zooecia , _ _ n 



U<z=0.10 mm. lfe=0.72 mm. 



Variations. The median avicularium is very variable on the same fragment; 

 it is quite small (Z=0.08 mm.) or very long (Z=0.25 mm.), but it always remains 

 elliptical (figs. 2, 5). 



The zoarium is square (figs. 2, 6) or quite rounded (figs. 4, 5). 



The ovicell does not entirely surround the aperture and is quite different from 

 the ovicell of other species of the same genus. 



Affinities. This species is well characterized by the arborescent form of its 

 zoarium. In its direct tremocyst and in the form of its aperture, it differs from 

 species of the same genus. 



It differs from Cellaria schrcil>( rsi Reuss. 1869. in which the zoarium is vin- 

 cularian in its median avicularium and its bifurcated 



