104 



Genus RHOMBOPORA. Meek. 



[Syn : Orthopora. Hall. Kty. : Rhombus, rhomb; poros, pore.] 

 (1872 Meek, Pal. Eastern Nebraska, p. 141.) 

 Bryozoum consisting of solid branches, with cylindrical 

 cells, which pass outward from ;ui imaginary axis ; cells with 

 transverse plates or tabulae; apertures separated by ridges, 

 which are often broad, and either continuous or unite to form 

 rhombic or polygonal cell spaces. Ridges bearing short 

 spines or nodes, and containing tubuli near the surface, from 

 the growth of the nodes. 



Rhombopora (?) transversa. (Hall.) (Fig. 52.) (Pal. 

 \. V.. Vol. VI., p. 1ST. Pis. LY., LYI.) (Simpson uses this 

 species to illustrate the genus. See Hand-book Pal. Bryo- 

 zoa, PI. XIX.) 



Distinguishing Characters. — Diameter of branches about 



1.75 mm. ; oval cell apertures in longitu- 

 dinal rows, diagonal rows, or irregularly 

 disposed; flat or slightly concave inter- 

 apertural space, with small, prominent 

 nodes or granules surrounding the aper- 

 tures; peristome prominent. 



Found in the "Hamilton group, at 

 West Hamburg, Erie County, N. Y." (Hall.) 



Rhombopora polygona. (Hall.) (Not figured.) (Pal. 

 N. V.. Vol. VI., p. 176.) 



Distinguishing ( naracters. — Infrequent b if urcations ; 

 widely diverging branches with diameter of 1.25 to 1.50 

 mm. : oval cell apertures, alternating in adjacent rows, so as 

 to make diagonal series at forty-five degrees to the axis; 

 angular or rounded, granulose interspaces, with conical 

 nodes at t he angles. 



Found in the "Hamilton group, West Hamburg, Erie 

 County, \. Y." | Hall); also four to five feet below the 

 Encrinal limestone, at Section 6, Eighteen Mile Creek 

 ( pare i. 



Rhombopora hexagona. (Hall.) (Fig. 53.) (Pal. N. Y., 

 Vol. VI., p. 178, Pis. LV.. LYI. Simpson, PI. XIX., Fig. 12.) 



Fig. 52. Rhombopora (?) 

 transversa. A fragment 

 natural sizi'. and a portion 

 of a branch enlarged, x 12 

 i after I [all and Simpson). 





