16^ 



Distiijo-uisJiing Chnrncters.— Rhombic or 

 hexagonal outline of the cell spaces; areas 

 surronnding- the cell apertnres {vestibular 

 nrea) smaller than in ])i'ece(ling s])ecies; 



1.11, IV I Fig. f3. Rhomhopora 



nodes at anglesal)sent : granules iewer and iw.rminna . Fragment 



. , . ,. . natural si/.c, and a por- 



more prominent tlian ni i)recedmg species, ti^n enlarged, x 13 rafter 



' '^ " ' Hall and Simpson ). 



-bound m the "Hamilton group, Eighteen 

 Mile Creek, Shore of Lake Erie, Erie Tounty, N. Y." ( Hall.) 



Rhomikipoka kktrtlata. (Hall.) (Fig. ~)-ir.) (Pal. 

 N. Y.. Yol. YI.. p. 179. Pis. LY.. LYI.) 



Distinguishing Charnvters. — Infrequent 

 bifm-cations; rhoniboidal cell spaces; oval 

 apertures; rathei- small vestibular ai-eas: 

 dividing ridge angular, with a row of minute X^^",^- i^hmnhopom 



^ ~ ~ reticnlata. Fragment 



granules along the crest and ])rominent S])in- HOT"el!ilrged"xil^af"- 

 ules at the intersections. ^""^ n^nana simpsou). 



Found in the ''Hamilton grou]». ^^'est Handjurg, Erie 

 Countv, N. Y.'' (Hah.) 



Rhombopora tortallnea. (Hall.) (Fig. r).").) (Pal. 

 N. Y., Yol. YI., p. 180, PI. LYI.) 



Distinguishing Characters. — Somewha t sinu- 

 ous growth ; infrequent bifurcations ; branches 

 with diameter of .6(J to .75 mm., and frecpiently 

 diverging at an angle of ninety degrees; oval 

 apertures more or less regnkirlv disposed in nine bop7ra'' tortau 



1 . T 1 ' ''«"• ^ 1~ (after 



or ten longitudinal rows, separated bv rounded, Haii and simp- 

 sinuous, or twisted ridges, bearing small nodes. 



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

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



Rhombopora i.ixeata. (Hall.) (Fig. T^{^.) 

 (Pal. N. Y., Yol. YI., p. 181, Pis. LY., LYI.) 



Distinguishing Cliaracters. — Branches often 

 diverging at angles of ninety degrees, diameter -pia. m. mom- 

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

 apertui-es, disposed in eight or nine longitu- c af Te?*^ riaif and 



T 1 T 11 1 1 • 1 1 ■ Simpson). 



dinal and parallel rows; thin, scarcely ele- 

 vated, peristome; prominent granulose ridges between the 



Fig. 5.5. Rhom- 



