DESCRIPTION OF PLATE VIII — CONTINUED. 509 



Page. 

 Fig. 10. Myalina wyomingensis 422 



A large left valve whose shape resembles fig. 8. 



Specimen seen from above. 



Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

 Fig. 11. Myalina wyomingensis 422 



A large left valve of a still different shape. 



Specimen seen from above. 



Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

 Fig. 12. Myalina wyomingensis 422 



A small left valve somewhat similar to fig. 10. 



Specimen seen from above. 



Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

 Fig. 13. Myalina wyomingensis 422 



A specimen from Texas which seems to belong to this species, and which closely 

 resembles the original of fig. 11. 



Right valve seen from above. 



Cisco division of the Upper Carboniferous: Graham, Young County, Tex. 

 Fig. 14. Myalina cuneiformis 420 



One of the type specimens of this species which I am enabled to figure through the 

 courtesy of the geological department of the University of Chicago. 



A right valve seen from above. 



Hermosa formation (?) : Ouray, Colo. ( Probably about the same locality and horizon-as 

 station 2195. ) 

 Fig. 15. Myalina cuneiformis 420 



Another type specimen, also loaned by the University of Chicago. 



Right valve; specimen seen from above. 



Hermosa formation (?) : Ouray, Colo. (Probably about the same locality and horizon as 

 station 2195. ) 

 Fig. 16. Myalina cineiformis 420 



Right valve from the Crested Butte region referred to Gurley's species. 



Specimen seen from above. 



Weber formation: Branch of Cement Creek, Crested Butte quadrangle (station 2314). 

 Fig. 17. Myalina cuneiformis 420 



Another specimen from the same locality as the preceding. The originals of both figures 

 are very imperfect, and the shape represented is, to a considerable extent, a matter of 

 restoration. 



Specimen seen from above. 



Weber formation: Branch of Cement Creek, Crested Butte quadrangle (station 2314). 



