1 65 



I 



Fig. 53. 

 hexagona 



Rhombopora 

 Fragment 



natural size, and a por- 

 tion enlarged, x 12 (after 

 Hall and Simpson). 



N. Y. 



(Hall.) 

 ) (Pal. 





Distinguishing Characters. — Rhombic or 



hexagonal outline of the cell spaces; areas 

 surrounding the cell apertures (vestibular 

 area) smaller than in preceding species; 

 nodes at angles absent ; granules fewer and 

 more prominent than in preceding species. 



Found in the "Hamilton group, Eighteen 

 Mile Creek, Shore of Lake Erie, Erie County 



Rhombopora reticulata. (Hall.) ( Fig 

 N. Y., Vol. VI., p. 179, Pis. LY., LYI.) 



Distinguishing Characters. — Infrequent 

 bifurcations; rhomboidal cell spaces ; oval 

 apertures; rather small vestibular areas; 

 dividing ridge angular, with a row of minute 

 granules along the crest and prominent spin- 

 ules at the intersections. 



Found in the "Hamilton group, West Hamburg, Erie 

 County, N. Y." (Hall.) 



Rhombopora tortalinea. (Hall.) (Fig. 

 N. Y., Vol. YI., p. 180, PI. LVI.) 



Distinguishing Characters. — Somewhat sinu- 

 ous growth ; infrequent bifurcations ; branches 

 with diameter of .60 to .75 mm., and frequently 

 diverging at an angle of ninety degrees; oval 



1 . , _ . _ . . Fig. 55. Rhom- 



apertures more or less regularly disposed m nine bopom tortau- 



r . o J I nea ^ x vz (after 



or ten longitudinal rows, separated by rounded, Han and sim P - 

 sinuous, or twisted ridges, bearing small nodes. 



Found in the "Hamilton group, Hamburg-on-the-Lake, 

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



Rhombopora lineata. (Hall.) (Fig. 56.) 

 (Pal. N. Y., Vol. VI., p. 181, Pis. LY., LVI.) 



Distinguishing Characters. — Branches often 

 diverging at angles of ninety degrees, diameter 

 about .6 mm.; elongate, oval, distant, cell 

 apertures, disposed in eight or nine longitu- 

 dinal and parallel rows; thin, scarcely ele- 

 vated, peristome; prominent granulose ridges between the 



Fig. 54. Rhombopora 

 reticulata. Fragment 

 natural size, and a por- 

 tion enlarged, x 12 (af- 

 ter Hall and Simpson). 



55.) (Pal. 



Fig. 56. Rhom- 

 bopora lineata. 

 Natural size, and 

 enlarged, x 12 

 (after Hall and 

 Simpson). 



