292 S. WELLER FAUNA OF THE FERN GLEN FORMATION 



Remarks. — This species of Evactinopora is one of the commonest and 

 most characteristic members of the Fern Glen fauna and is highly varia- 

 ble in form. Among 146 bases preserving all of the rays, 3 have four 

 rays, 39 have five rays, 44 have six rays, 37 have seven rays, 18 have eight 

 rays, and 5 have nine rays. Other characters in which the specimens 

 vary are the relative size of the central disk and the thickness of the rays 

 themselves. The combined characters of all of these examples seem 

 almost to include the characters of the three species, E. sexradiata 

 M. & W., E. quinqueradiata Ulr., and E. radiata M. & W., but Ulrich's 

 figures of E. sexradiata best exhibit the most usual features of the spe- 

 cies. E. quinqueradiata, as interpreted by Ulrich, has relatively longer 

 and more slender rays, and E. radiata, as interpreted by the same author, 

 has a much larger disk and is much higher in proportion to the diameter 

 of the base. 



BRACHIOPODA 

 CRANIA MISSOURIENSIS n. sp. 



Plate 12, figure 1 



. Description. — Shell rather large, subcircular in outline. The dorsal 

 valve depressed convex, the apex rather obscure and situated excentrically 

 about one-third the length of the shell from the anterior margin. Sur- 

 face of the shell marked by rather fine but more or less irregular and 

 uneven concentric markings. 



The dimensions of the type specimen are: Length, 17 millimeters; 

 width, 17 millimeters. 



Remarks. — The type of this species has grown upon the interior of the 

 pedicle valve of a Productus. The central portion of the shell is de- 

 pressed convex, but toward the margins it becomes concave, because of 

 the strongly concave surface to which it is attached. Attached to some 

 other flatter surface the shell would doubtless be depressed convex 

 throughout. The species seems to be distinct from any of the described 

 forms, although one or two Lower Mississippian species have been so 

 briefly described without illustrations that they can not be recognized 

 except through a study of the type specimens. 



LEPT2ENA RHOMBOIDALIS {Wilckens) 

 Plate 12, figures 2-3 



1821. Anomites rhomboidalis Wahlenberg, Acta. Society of Upsala, volume 3. 



page 65. 

 1836. Product a analoga Phillips, Geology of Yorkshire, volume 2, page 215, 



plate 7, figure 10. 



