126 



NORTH AMERICAN INDEX FOSSILS. 



apart, arranged in spirally ascending lines or irregularly; strong 

 peristomes ; interapertural spaces smooth ; stems solid or encrust- 

 ing crinoids. 



Rochester shales of New York and Ontario. 



Fig. 184, a. Chilotrypa ostiolata, branch Y\G. 

 natural size and enlargement. larged 



[84, b. Chilotrypa ostiolata; en- 



XXIII. Buskopora Ulrich. 

 Like Fistulipora, but with pronounced lunarium projecting as 

 bidenticulate process nearly half across aperture. Devonic. 



33. B. dentata Ulrich. (Fig. 182,/.) Devonic. 

 Incrusting or free expansions, with concentrically wrinkled 



epitheca on lower side ; apertures in regular diagonally intersecting 

 lines ; slightly elevated maculae with smooth centers, at intervals 

 of 5 mm. 



Hamilton of Falls of the Ohio. 



XXIV. Meekopora Ulrich. 

 Bifoliate (two layers growing back to back), zocecial tubes gently 

 curving outward, opening obliquely, distally pointed, and with 

 numerous diaphragms. Convex elevations or ovicells with small 

 apical opening occur at intervals. Silur.-Carb. 



34. M. clausa (Ulrich). (Fig. 182, £\) Carbonic. 

 Compressed branches, surface with substellate maculae, between 



which the zooecia are uniformly distributed in very regular oblique 

 series ; interapertural space flat or slightly concave, usually smooth 

 or minutely pitted or granular, vesiculose in lower part. 

 Chester of Illinois and Kentucky. 



