PLATE I. 



Page, 



Fig. 1. Menophyllum vlrichanum 271 



A nearly perfect specimen, slightly broken at the tip, showing the rapid expansion and 



curved shape characteristic of the species. 

 Side view. Somewhat turned toward the eye, actual curvature diminished by perspective. 

 Ouray limestone: Cascade Creek, in the Engineer Mountain quadrangle (station 2379). 



Fig. 2. Menophylldm ulrich anum ■. 271 



A cast in chert of the calice of an individual belonging to this species. 

 Cast seen from above. The relation of the primary to the secondary septa, the main 

 fossula (that in the center), the two secondary fossulte (especially that on the left) , and 

 the tripartite arrangement of the septa resulting therefrom, are well shown. 

 Ouray limestone: Canyon Creek, in the Needle Mountains quadrangle (station 2386). 



Fio. 3. Spiriperina solidirostris ? 294 



A small dorsal valve preserved as a east in chert, considerably enlarged. The punctate 

 character of the shell is well shown by the pustules on the cast. The specimen is too 

 young to show clearly the slight median division of the fold. 

 Specimen seen from above. 

 Millsap limestone: Perry Park (station 2389). 



Fig. 4. Spiriperina solidirostris ? 294 



A somewhat larger ventral valve, similarly preserved and also enlarged. The incipient 

 plication in the middle of the sinus is shown in this individual, also the impression of 

 the median septum and dental lamellae. 

 Specimen seen from above. 

 Millsap linaestone: Perry Park (station 2389). 



Fig. 5. Seminula subquadrata? 296 



Small example; larger specimens closely resemble Seminula subquadrata Hall. 



Ventral valve seen from above. 



Leadville limestone: Leadville district. Oolite mine, Leadville (station 2375). 



Fig. 6. Cran^na subblliptica 299 



An example from the typical locality, presenting the usual characters. Preserved chiefly 



as an internal cast, with small fragments of the shell adhering. 

 Dorsal view of specimen. 

 AVaverly group: Sciotoville, Ohio. 



Fig. 7. CRANiENA subelliptica 299 



Another example preserved as an internal cast, having the usual shape and size and showing 



many of the structural features of the genus. 

 Dorsal view. This specimen shows the two dental lamellae of the ventral valve. The 

 broken part at the right is along one of these. The posterior portion of the cast of the 

 dorsal valve has been chiseled away so as to show the hinge plate with its two carinse, 

 which project as the two limbs of the crura. 

 Waverly group: Sciotoville, Ohio. 

 484 



