PREFACE. XI 



tions of California. The field-work was continued in Kern, 

 Tulare, and Inyo Counties, by Mr. D'Heureuse and party; by 

 Mr. Hoffmann and party in Mariposa and Tuolumne, and by 

 Mr. Wackenreuder in the High Sierra, between Alpine and 

 Plumas. Mr. Gabb, accompanied by Messrs. Wilson, Lolir, 

 and Poston, explored the White Mountain Range, on the 

 borders of California and Nevada. They continued their 

 work east into the latter State (not at the expense of Cali- 

 fornia), carrying their topographical and geological recon- 

 noissance as far as the 116th meridian, including a large 

 portion of the area between the 37th and 39th parallels. 

 They continued in the field until the end of October, as long 

 as the season would permit. Their collections embraced a 

 considerable number of fossils of various geological ages, from 

 Lower Silurian to Triassic. 



A part of these was unfortunately lost in transitu ; of the 

 remainder, a portion has been worked up by Mr. Gabb, and 

 the results will be published in the Conchological Journal. 

 All the Palaeozoic fossils collected by the Survey, together 

 with a considerable amount of palgeontological material from 

 rocks of this age, collected by different members of the 

 corps, and a considerable number of interesting specimens 

 contributed by others, have been placed in Mr. Meek's hands 

 for examination, with a view to future publication of the 

 results by the Survey, or otherwise. We are especially in- 

 debted to Mr. J. E. Clayton for an interesting collection from 

 Silver Peak and vicinity, and to Mr. S. S. Lyon for one 

 from the neighborhood of Pahranagat. Mr. Gorham Blake 

 and Mr. A. Blatchly have also contributed valuable Palaeo- 

 zoic fossils (as well as Triassic and Jurassic), from various 

 localities in Nevada. 



The occurrence of rocks of Upper and Lower Silurian 



