NATURAL HISTORY. 557 
inches in length, and are exceedingly poisonous, sometimes 
fatal. Then there is the venagron, as the Mexicans call it, a 
black insect about two inches in length, also very poisonous ; 
and lastly, the alacran, a species of scorpion, the most venomous 
of all. These last, fortunately, are chiefly confined to the city 
of Durango ; where, owing to their numbers, and the fatality 
which attends their sting, a bounty of six cents is given by the 
government for every one killed. We close this catalogue 
with the rattlesnake, which needs no description. This creature 
is found every where, from the Gulf of Mexico to the Pacific, 
alike in grassy, rocky, and desert regions. Hundreds of them 
were killed by our party ; yet I am not aware that any of us 
were bitten. T'wo horses that were bitten died. All the 
other reptiles and insects of which I have spoken are found 
throughout the countries contiguous to the Boundary, and were 
seen almost daily. Thus has nature adapted a numerous class 
of animals for the otherwise solitary desert, where they enjoy 
undisputed sway. These plains also abound in moles, rats, 
mice, rabbits, and other burrowing animals ; sometimes to such 
an extent, that it 1s dangerous to pass over them with horses 
and mules. Many specimens of the lesser mammalia were 
brought home by the Commission, as well as a collection of 
reptiles and insects. Of reptiles, a very large number was 
discovered which are entirely new. ‘This collection is now in 
the cabinet of the Smithsonian Institution at Washington. 
One of the most interesting animals met with on the prai- 
ries and high table-lands, is the “* prairie dog,’ which is in 
fact no other than a marmot, having no character in common 
with dogs. Its look and habits are totally different. The 
Canadian trappers used to call it a “ petit chien ;” and this, to- 
gether with the noise it makes, which however, is more of a 
chirp or yelp than a bark, has caused it to receive the name 
of ‘ prairie dog.’ ; 
The first community of these little creatures we met with 
was in Texas, near Brady’s Creek, a branch of the Colorado 
