CHAPTER VI. 



LIFE HISTORY OF LAKE LAHONTAN. 



The fossils obtained from the sediments and tufa deposits of Lake La- 

 hontan consist of the bones of mammals and fishes ; the shells of fresh- 

 water mollusks and of ostracoid crustaceans ; the larval cases of a caddis 

 fly ; a single chipped implement of human workmanship ; and vegetable 

 vestiges of a doubtful nature. 't/o , itfj, 



Mammalian bones were obtained at a number of localities in the sides 

 of the Humboldt and Walker River canons, and, with the exception of a 

 single vertebra found in the medial gravels, they were all derived from the 

 upper lacustral beds. These fossils were submitted to Prof O. C Marsh for 

 determination, but only a partial report as to their character has been ren- 

 dered. So far as determined they include a proboscidian (elephant or mas- 

 todon), a horse, an ox, and a camel. The fossils were usually detached 

 and scattered through the sediments, more than one or two bones of the 

 same individual being seldom found at a single locality, except in the case 

 of the elephant or mastodon bones obtained in the Humboldt Canon near 

 Rye Patch, where nearly an entire skeleton must have been entombed ; 

 many of the bones had been removed, however, before the localitj^ was 

 visited by the writer. The failure to obtain mammalian remains from the 

 lower lacustral deposits is of but little weight as negative evidence, for the 

 reason that the beds are imperfectly exposed ; a more critical search would, 

 perhaps, reveal an abundance of fossils.'"' 



'^I would suggest in this connection tliat the disappearance of a number of large mammals from 

 thp fauua of this continent since the deposilion of the npper Lahontan sediments may have been 

 caused by the extreme aridity which followed the last recession of the lake. An intensely arid climatf< 



238 



