Rrieeland.] 376 [April 15. 



the pyramidal, castle-like and fantastically shaped forms, known as 

 " buttes," of various colors, horizontally stratified, and hundreds of 

 feet high, showing what was once the general level of the country, 

 now so nearly washed away. The track of the road here is, there- 

 fore, for hundreds of miles over the bed of a tertiary lake. 



The strata on the west correspond to those on the east of the 

 ranges, showing that they are great anticlinal folds, whose strata 

 slope in opposite directions, the numerous deep valleys being worn in 

 the fracture of the central line of elevation. 



The " Laramie Plains " is a mountain prairie, at an average eleva- 

 tion of six thousand five hundred feet, comprising an area of six thou- 

 sand seven hundred and fifty square miles, and an excellent grazing 

 region. Beyond these plains traces of coal begin to be seen. The coal 

 at Carbon, eighty miles from Laramie, is very near the track, abun- 

 dant, of excellent quality, a compact tertiary lignite. The coal ex- 

 tends for many miles in all directions, showing that this desert was, 

 at a comparatively recent geological epoch, covered with luxuriant 

 vegetation. At Green River occur the great bluffs of bituminous 

 shales, mentioned in Hayden's Report for 1872, p. 337, which have 

 recently been profitably used for the extraction of an excellent min- 

 eral oil. 



He showed pictures of the Echo and Water canons, near Salt 

 Lake, including the Salt Lake, all of which region, including the 

 Salt Lake basin, was once, according to Hayden, a vast fresh water 

 lake; the waters were slowly evaporated, leaving the terraces to 

 mark the changes and the former levels of the lake — briny, indeed, 

 not from the sea, which had been shut out from this region long 

 before, but from salt springs and concentration in this closed basin. 

 The lake itself is very old, and part of the great water area once 

 extending from the Wahsatch Mts. on the east to the Sierra Nevada 

 on the west, from the mountains of Columbia on the north to those of 

 Colorado on the south. The researches of Fremont, Stansbury, the 

 Pacific Railroad geologists, and Hayden, all confirm the above con- 

 clusions. 



ERRATA ET ADDE]ST>A. 



Page 109, line 112. For " Myiadestes townsendi" read " Pnainopepla ni- 



tens." 

 Page 109, line 33. For " capalis " read " carpalis." 

 Page 118, line 15. For "36" read " 37." 

 Page 241, line 5. For " black, edged" read "black-edged." 

 Page 243, line 30. For " borealis " read " Faustina." 



Some of the nests and eggs described in the paper of Dr. Brewer, pp. 106-111, 

 were described by Dr. Coues in the "American Naturalist," after its presentation 

 but before publication. 



