DESCRIPTION OF PLATE I CONTINUED. 485 



Page. 

 Fig. 8. Cran^na subelliptica var. haedingensis 299 



A ventral valve of somewhat near the average shape and size, preserved in chert. Other 



specimens are more rotund. 

 Specimen seen from above, showing the two dental lamellse. 

 Millsap limestone: Harding's quarry, Canyon, Colo, (station 2370). 



Fig. 9. Cean^na subelliptica var. haedingensis 299 



Dorsal valve of the same species. 



Specimen (an internal cast) seen from above. A very faint median septum is shown; 

 the marks on either side are connected with the muscular attachment. Near the 

 posterior margin appear the cavities left by the socket plates. 

 Millsap limestone: Garden Park, Colo, (station 2365). 



Fig. 10. Ceanjen a subelliptica var. haedingensis 299 



Ventral valve of somewhat more than the average size and proportionate length. 

 Specimen seen from above. This example also is preserved as an internal cast in chert. 

 Millsap limestone: Garden Park, Colo, (station 2371). 



Figs. 11 and 11a. Eumeteia woosteei 302 



Type and original specimen figured by White. Artificial impression from a natural mold. 

 Fig. 11. Ventral view. 



11a. Side view. 

 Pebbles in the Wyoming sandstone (?), 32 miles west and 18 miles north of Greeley, Colo, 

 (station 2364). 



Fig. 12. Myahna keokuk 309 



A left valve believed to belong to this species. Preserved as a cast in chert. 



Specimen seen from above. 



Ouray limestone: Near Cascade Creek, Engineer Mountain quadrangle (station 2382). 



Fig. 13. Streblopteeia media 307 



An isolated right valve referred to Herrick's species. 



Specimen seen from above. 



Millsap limestone; Perry Park, Colo, (station 2389). 



Fig . 14. Aech.s;ocidaeis oura yensis ^ 329 



A somewhat imperfect specimen partially embedded in matrix, showing the peculiar 



and characteristic ornamentation. 

 Specimen seen from the side, and somewhat enlarged. 

 Hermosa formation (?): Ouray, Colo, (station 2194). 



Fig. 15. Prismopora triangulata 340 



A group of specimens partially embedded in limestone. This is the specimen originally 



figured by White. 

 Specimen somewhat enlarged, showing the external characters of the species. 

 Middle division of the Carboniferous series: Yampa Plateau, northwestern Colorado. 



Fig. 16 to 16b. Oethotichia schuchertensis 345 



The most perfect specimen obtained, preserving both valves. 



Fig. 16. Ventral view. The shape and peculiar surface characters are well shown, 

 also the septum and strong dental plates of the ventral valve. 

 16a. Anterior view, showing the shape and relations of the valves and the somewhat 



different character of their surface ornamentation. 

 16b. Side view of the same. 

 Weber shale: Glen wood Springs, Colo, (station 2193a). 



