1 64 NORTH AMERICAN INDEX FOSSILS. 



sharp, non-poriferous ; apertures subcircular, with unequal peri- 

 stomes. 



Keokuk of Iowa ; Warsaw of Illinois. 



155. G. (Phractopora) megastoma (Ulrich). Mississippian. 

 Cups large ; apertures large, subcircular, most pronounced at 



angles of cups; maculae conspicuous often on broad elevations; 

 apertures larger near maculae ; generally only fragments of cups 

 found. 



Keokuk of Illinois and Iowa ; Waverly of Ohio. 



XCI. Evactinopora Meek and Worthen. 

 Free, of four or more vertical leaves of cruciform or stellate 

 arrangement; rays united, thick and nonporiferous in basal por- 

 tion, free, with subcircular apertures on both sides in upper part ; 

 vesicular interspaces, solid at surface. Miss. 



156. E. grandis Meek and Worthen. (Fig. 214,^.) Mississippian. 

 Large, transverse diameter probably 7 inches ; rays 4 ; apertures 



small, regularly arranged in quincunx order, separated by about 

 twice their width. 



Burlington of Iowa and Illinois. 



157. E. radiata Meek and Worthen. (Fig. 214,/.) Mississippian. 

 Rounded below, above of eight solid subcarinate rays, with cir- 

 cular pores on thin portions of rays ; greatest diameter, from tip to 

 tip of rays, 22.5 mm. 



Keokuk of Missouri and Kentucky. 



XCII. Actinotrypa Ulrich. 

 A thin, bifoliate expansion, with 8 to 10 vertical, septa-like ridges 

 in aperture, extending along sides of vestibule. Miss. 



158. A. peculiaris (Rominger). (Fig. 214, h.) Mississippian. 

 Apertures regularly arranged in diagonal intersecting series, 



floriform from tooth-like projection of pseudo-septa; peristomes 

 raised ; minutely punctured or granular subcircular maculae char- 

 acterize the surface at variable intervals. 

 Keokuk of Missouri, Iowa and Illinois. 



XCIII. WORTHENOPORA UlHch. 



Bifoliate, branching or palmate, with regularly arranged elon- 

 gate rhomboidal zooecia with semi-elliptical apertures, the trun- 



