NORTH AMERICAN EARLY TERTIARY BRYOZOA. 229 



This species resembles closely AWv, /;,///,/ rosselii Audouin, 1826. a recent form, 

 which, however, appears first in the Priabonian of Vicentin, Italy. Rossdiana 

 parvipora differs, however, in its smaller micrometric measurements (Z.s=0.36 mm. 

 instead of 0.44 mm.) and principally in its small transverse opesium. 



Occurrence. Vicksburgian ("Chimney rock" of Marianna limestone): One 

 mile north of Monroeville, Alabama (rare). 



Bolotypc.G&t. No. 64253, U.S.N.M. 



Genus FLORIDINELLA Canu and Bassler, 1917. 



1917. FloridineUa CANU and BASSLER, Synopsis of American Early Tertiary Cueilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 28. 



The ovicell is endozooecial and separated from the zooecia by a fold The 

 polypidian convexity is not prominent. The opesiular indentations are large and 

 rounded. The opesium is constricted by two symmetrical lateral teeth at the level 

 of the opercular articulation. 



Genotype. FloridineUa vicksbnryica Canu and Bassler, 1917. 



This genus is a true Floridina -without onychocellarium. The following species 

 must be classed in this genus : 



FloridineUa (M arginaria) deshayesi Hagenow, 1851. 



FloridineUa (Membrani.pora) formosa Eeuss, 1874. 



FLORIDINELLA VICKSBURGICA Canu and Bassler, 1917. 



Plate 82, figs. 17-26. 



1917. FloridineUa vicksburyica CANU and BASSLER, Synopsis of American Early Tertiary 

 Cheilostome Bryozoa. Bulletin United States National Museum, p. 28, pi. 3, fig. 3. 



Description. The zoarium is unilamellar, hollow, cylindrical, and incrusts the 

 stems or small roots of algae. The zooecia are elongated, distinct, separated by 

 a deep furrow ; the mural rim is incomplete, rather broad, distinct from the crypto- 

 cyst. The cryptocyst is shallow, smooth, or finely granular, longer than the 

 opesium; the polypidian convexity is but slightly projecting; the opesiular indenta- 

 tions are large, symmetrically rounded; the opesium is elongated, constricted 

 superiorly by two lateral teeth placed at the level of the operculum. 



,, t/i 00.20 mm. . r 7,3=0.50 mm. 



Measurements. Upesium 7 . , Zooecia . 



lZ0=0.16mm. 1/2=0.30-0.40 mm. 



Variations. Species with tubular zoaria are quite polymorphic, for the zooecia 

 are easily deformed on account of irregularities in the substratum. In the present 

 species there are wide zooecia (fig. 21) and narrow zooecia (fig. 19). The opesium 

 becomes very small and the opesiules become linear (fig. 22). We have observed 

 some cases of total regeneration (fig. 26) and closed zooecia perforated by a slit 

 or by a pore (fig. 26). 



The noncelluliferous face (figs. 23-25) always presents small hydrostatic tuber- 

 osities designed to detach the zoarium from the substratum, to creep on the 

 ectocyst, and to increase the volume of the zoarium. Here the zooecia are dis- 



