PLATE XVIII. 



Pane. 

 LlNGULA MYTILOIDES ? ............................................. 279 



Fig. 1. View of a specimen from the lower portion of the Carboniferous formation, north of 

 Pinto Peak. 



DISCIXA NEWBERRYI .......................................... 213 



Figs. 2, 2. Dorsal and ventral valves of a form from the shale in Secret-canou-road Canon, 

 doubtfully referred to this species, enlarged to two diameters. 

 Dorsal valve from Richmond Mountain. Natural size. 



SPIRIFERA LEIDYI 



Figs. 4, 4 a. Dorsal and ventral views of the average size specimens found at Richmond 

 Mountain. 



ATHYKIS HIKSUTA ..................... * .................................................... 222 



Fig. "). Dorsal view of a specimen from Coal Hill, Pancake Mountains. White Pine County, 

 Nevada. 



CAM AROPHORIA COOPERENSIS .............................................................. ->>4 



Fig. 6. Ventral view of a specimen from Richmond Mountain. 



SPIRIFERA ANNECTANS ...................................................................... 216 



Figs. 7, 7a. Dorsal and ventral views, showing the rounded cardinal extremities, and the 

 coarse plications. 



RHYNCHONELLA EUREKENSIS ............................................................... 223 



Fig. 8. Lateral view of a specimen which is slightly crushed. 

 Sa. Ventral view of the same. 



8 b, c. Ventral and dorsal views of a smaller example. 



ATHYRIS ROYSSII ........................................................................... 280 



Fig. 9. Dorsal view of a specimen from the canon north of Pinto Peak. 



9 a. Lateral view of the same. 



SPIRIFERA NEGLECTA ....................................................................... 217 



Fig. 10. View of a ventral valve, from Richmond Mountain. 



SPIRIKERA TRIGONALIS ...^ ................................................................. 215 



Fig. 11. View of a ventral valve, from which the outer shell is largely removed. 



SPIRIFERINA CRISTATA ...................................................................... 218 



Fig. 12. Dorsal view of a specimen from the Chester limestone of Chester, 111. Introduced 



for comparison. 



13. Same view of a specimen from the upper portion of the Carboniferous Group in the 

 Eureka District. The spine bases are not shown in the figures, although quite 

 prominent on the shells from each locality. 



STREPTORHYNCHTJS CRENISTRIA ............................................................. 279 



Fig. 14. View of a strongly striate form, found at Richmond Mountain. 



