NORTH AMERICAN EARLY TERTIARY BKYOZOA. 



209 



Affinities and variations. In reality the zooecia are not dimorphous, for their 

 micrometric dimensions are very similar; but there are actually two kinds of 

 opesia. One is large, elongated, elliptical, with neither polypiclian convexity, nor 

 opesiular indentations; the other is small, transverse, with polypidian convexity and 

 opesiular indentations (zooecia a). These two kinds of zooecia occur without 

 apparent order, and we are in ignorance regarding the use of the large opesia. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (very rare); 

 Rich Hill. Crawford County, Georgia (common) ; Eutaw Springs, South Carolina 

 (common). 



Upper Jacksonian (Ocala limestone) : Along the west bank of Sepulga River. 

 Escambia County, Alabama (very rare). 



Coti/pes.Cat. Nos. 63961-63963, U.S.N.M. 



..sol 



n. 



A *24 



FIG 57. Genus Rectonycliocella Canu and Bassler, 1917. 



A-E. Reclonyclwcella solida. Nordgaard, 1907. A. Zooecia and onychocellariuru, X 24. 

 B. Longitudinal section of a zooeciurn, X 36. fir, basal wall; dp, distal dietella ; dv, transversal 

 wall ; fi-, frontal wall ; Ip, lateral septulae. C. Sketch showing nmndible in place, X 24. k, lunate 

 ehitinous mass: me, corneous membrane; onto, passage of occlusor muscles; r, rachis. D. Ele- 

 vator muscles of the mandible, X 70. E. Opercular valve, X 50. (A-E after Norgaard, 1907.) 

 ect, ectocyst; op, opercular valve; set, sclerite. 



Genus RECTONYCHOCELLA Canu and Bassler, 1917. 



1917. I'l'i-tHiiii'-lifji-flla CANU and BASSI.EB, Synopsis of American Early Tertiary Cheilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 25. 



The retractor muscles of the polypide are attached in the median axis of the 

 zooecia. The opesiular indentations are symmetrical. The onychocellaria are 

 straight, and their opesium presents a posterior part, narrow and denticulated: 

 the mandible is composed of two membranes. The zooecium is closed by an 

 opercular valve. The mural rim is not separated from the cryptocyst. 



Genotype. Onychocella solida Nordgaard, 1907. 



Range. Jacksonian Recent. 

 55899 19 Bull. 106 14 



