510 PALEONTOLOGY OF ILLINOIS. 



EVACTINOPORA SEXRADiATA Meek and Worthen. 



PL LXXIII, fig. 2-2&. 

 Evactinopora sexradiata M. W. 1868. Geol. Surv. 111. vol. 3, p. 502. 



This species differs from the preceding in being a little wider 

 and much more depressed, and constant in having only six 

 rays. The zooecia apertures are also larger, there being only 

 about six in three mm. In a basal view the rays are much 

 longer and more slender. Beside the whole zoarium appears to 

 be much more delicate in its proportions. 



The example figured by Meek and Worthen (loc. cit.) having 

 only five rays, does not belong to this species, but to E. 

 q uin q ueradiata. 



Position and locality: Burlington group. Burlington, Iowa. 



EVACTINOPORA QUINQUERADIATA Ulrich. 



PL LXXIII, flg. 1. 



Zoarium with five thin bifoliate rays, varying in different ex- 

 amples in thickness from 2 to 4 mm., in width from 20 to 60 

 mm., and in height from 15 to 40 mm. The body formed by 

 the union of the rays comparatively very small. Kays increas- 

 ing very gradually in thickness from the free outer margin to 

 the body, sharp on the lower margin, which curves very slightly 

 upward toward the extremity, where it forms nearly a right 

 angle with the more curved upper margin. Zooecia apertures 

 small, sub-circular, about twice their width apart, arranged in 

 regular intersecting series, about six in three mm. 



This species is readily distinguished from E. sexradmta, M. & 

 W., by its much larger size, five instead of six rays, and com- 

 paratively more depressed form. 



A section in the rock showing only the upper portion of the 

 rays of an example of this species was erroneously figured in 

 Vol. Ill, on plate XVII, as E. sexradmta, by the authors of 

 that species. 



Position and locality: Burlington limestone. Burlington, 

 Iowa, and Montezuma, 111. 



