72 



BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



Wortmau's skill. Upon opening the snakes one was found to contain six fishes. The 

 headwaters of the Smoky Hill and Big Horn rivers abound in this aquatic Eritaenia 

 radix. 



Doctor Coues (1878, 278) has also observed the habits of radix in 

 North Dakota and Montana: 



In the more fertile portions of the Red River Valley itself, throughout the Red River 

 region, from Peml)ina to where the Coteau de Missoviri crosses the line, it is the charac- 

 teristic 0])hidian, the ])rincipal and almost only representative of its order, outnum- 

 bering all the others put together. * * * 



In the more fertile portions of the Red River Valh-y itself this snake may be found 

 almost anywliere in the brusli and herbage. Out on the drier prairie l^eyond it is 

 chiefly confined to the pools and streams, or their immediate vicinity. Numbers are 

 found basking together on the muddy borders of the sloughs or among the masses of 

 aquatic vegetation where they find ample subsistence during the summer months in 



Fig. 23.— Habitat i)F Thamnopiiis radi.x and T. sirtai.ls paiuetalis. Slough (ottlet to P'i.bow 

 Lake), Clay Cointy, Iowa. The margin df these grassy swamps is apparently the most 

 favorable habitat for t. radix in the prairie-plalna region, and with it is found associ- 

 ated t. sirtalis p.\^rietalis. 



tadpoles, young frogs, and various water insects. They are themselves preyed upon 

 by hawks, especially the Marsh Harrier {Circus cyancris hudsonius) and Swainson's 

 Buzzard {Bitteo swainsoni). They are less active than some of the slender species, 

 are readily caught, and when captured make little or no resistance. Only the largest 

 individuals assume for the moment a defensive attitude and attempt to bite; most 

 may be at once handled with impunity. 



My own observations on the habits of radix in northwestern Iowa 

 agree in the main with those of Doctor Coues. The topograph}^ of 

 this region is characteristically glacial, and consists principally of 

 moraines with intervening lakes, ponds, or swamps, according to 

 the depth of the depressions. The swamps, locally known as 

 "sloughs" (fig. 23), are characteristic of the prairie region. The 



