300 



GEOLOGY. 



were much alike. Those of the interior and western portion of America 

 appear to have been more nearly correlated with the faunas of central 

 and eastern Eurasia. Richthofen found typical Cambrian fossils in 

 eastern China, and his observations have been confirmed and extended 

 recently by Willis and Blackwelder. Fossils of the Cambrian aspect, 

 but somewhat divergent from the European types, occur in the Salt 



Fig. 128. — Upper Cambrian Fossils. Trilobites: a, Dikellocephalus pepinensis, Owen. 

 Brachiopods: b and c, Plect^rthis newtonensis Weller, internal casts of the brachial 

 or dorsal and pedicle or ve~ + ral valves; e and /, Lingulepis pinniformis Owen, 

 views of the two valves; g, Obolella polita Hall; m and n, Billingsella coloradoensis 

 (Shum.). Gastropods: h, Holopea sweeti Whitfield; i and /, Bellerophon antiquatus 

 Whitfield, two views of the same shell; k and I, Ophileta primordalis Wlnchell, 

 two views of the same shell. Pteropod: d, Hyolithes. 



range of India, while more typical forms, embracing Olenellus and 

 Dikellocephalus, are found in south Australia and Tasmania. The Upper 

 Cambrian fauna is found in northern Argentina. Taken altogether 

 these facts show that the same general types of life prevailed through- 

 out the world, so far as known, while there were notable provincial 

 variations then, as at all later stages. 



