1 66 NORTH AMERICAN INDEX FOSSILS. 



forming with growth tubular vestibules, separated by compact^or 

 horizontally laminated interspaces; peristomes equally elevated, 

 or highest posteriorly. Siluric. 



161. D. dichotoma Hall. (Figs. 216, a, 216, b.) Siluric. 

 Regularly bifurcating, generally filled with rock matrix, or 



crushed ; interior of hollow branches, transversely striated, apertures 

 in regularly ascending spiral lines, strongly 

 elevated posteriorly. 



Niagara (Rochester) of New York, etc. 



XCVI. Stictotrypa Ulrich. 



Ramose, not pointed at the base; 

 branches dichotomously dividing, narrow, Fig. 216, a. Diamesopora 

 compressed, with circular or elliptical aper- &*««** enla ^ ed showin S 



. oblique peristomes. 



tures, evenly elevated peristomes, and flat 



or concave interspaces of horizontally laminated solid tissue. Sil. 



162. S. punctipora Hall. (Fig. 214, k.) Siluric. 



Flattened, bifurcating; apertures min- 

 / ~~\ ute, punctiform with elevated peristomes 



> arranged in diagonal series. 



Niagara (Rochester) of New York,etc. 



y .y f XCVII. Paleschara Hall. 



f I /\ Thin incrustations with short, direct, gen- 



f erally thin-walled zocecia, with long, hex- 



• I I / agonal or polygonal apertures. Ord.-Dev. 



\y 163. P. incrustans Hall. Lower Devonic. 



On shells [Spitifer perlamellosus) or other 

 bodies ; 0.1 to 1.0 mm. thick ; cells polyg- 

 Fig. 216, b. Diameso- ona i [ n contact; walls thick, sometimes 



para dichotoma natural size, wUh Qbtuse inose ocesses at the angleSf 

 showing axial hollow. ' / 



Helderbergian of New York, etc. 



MESOZOIC AND CENOZOIC SPECIES. 

 Order CYCLOSTOMATA. 

 XCVIII. Filifascigera d'Orbigny. 

 Irregularly branching, repent zoaria, with apertures in clusters 

 of from two to five or more. Cret.-Tert. 



U 



