REPORT ON THE NATURAL HISTORY OF THE UNITED STATES 

 GEOLOGICAL AND GEOGRAPHICAL SURVEY OF THE TERRI- 

 TORIES, 1874. 



By Ernest Ingersoll, Zoologist. 



Cambridge, Mass., March 1, 1875. 

 Sir : I herewith submit the subjoiued report of zoological work done 

 during the season of 1874 in connection with the survey under your 

 charge, and have the honor to be, with the highest respect, yours, &c., 



EENEST INGERSOLL, 



Zoologist. 

 Dr. E. V. Hayden, 



U. 8. Geologist, Washington, D. C. 



The material herein reported upon is a collection, chiefly of mollusks, 

 made by the writer, in connection with the photographic division of the 

 survey, during the months of July, August, and September, 1874. I 

 was assisted by Master Frank Smart, of Washington. 



Our route lay from Denver west into Middle Park, thence south up 

 the valley of the Blue to Hoosier Pass, leading us into South Park, 

 from which we crossed over to the Arkansas, and thence through Poncha 

 Pass into San Luis Park, and across to Saguache. From here the road 

 was west to the Los Pinos Indian agency, and then southwest through 

 Antelope Park to Baker's Park, in the high mountains. 



At this point the camp was stationed ; and leaving Mr. Smart to collect 

 here, I accompanied Mr. Jackson on a side-trip of nearly three weeks' 

 duration, made southwest into the valley of the Eio San Juan, at the ex- 

 treme corner of the Territory. On our return trip from Baker's Park, we 

 followed the Rio Grande to Del Norte, thence struck across the San 

 Luis plain to the " sand-hills," through Musca Pass, Huerfano Park, 

 Wet Mountain Valley, and Oak Creek, and finally came to CaQon City, 

 Avhere I left the party. 



Collections were made at nearly every camp on the whole route, and 

 that they do not make a greater aggregate is due to the inexperience of 

 the writer, the short time he was in the field, the haste with which the 

 party moved, and not a little to the comparative scarcity of those ob- 

 jects in which he happened to take the most interest, and most desired 

 to have completely represented. In such cases, in the absence of speci- 

 mens or affirmative evidence, he is able to show a certain amount of 

 negative evidence, which may be of value in future deductions. 



I append a list of the localities, remarking upon elevation and so 

 forth, at which collections were made. The absence of any camp, as 

 Nos. 12-16, from this list does not necessarily imply that I was idle, 

 but that nothing of importance reached home from that locality. 



