39 



2. Aspidonectes spinifer Agass. 



Frequent in both the Musselshell and Yellowstone Rivers, and also 

 seen in some of the smaller streams. 



LACERTILIA. 



3. Sceloporus consobrinus B. & G. 



A single specimen was taken on the Yellowstone, near Camp 

 Thorne, and a few others were seen. Apparently quite rare. 



4. Phrynosoma Douglassi Wagl. 



Occasional throughout the region traversed, but very common only 

 at a few looalities. 



OPHIDIA. 



5. Caudisona confluenta (Say). 



Common, especially in the Bad Lands of the Little Missouri and 

 along the Yellowstone. This species many times outnumbers all the 

 other Ophidians together. Several hundred were killed by the dif- 

 ferent members of the Expedition, but notwithstanding its abund- 

 ance the only casualty resulting from it was one horse bitten. On 

 the Expedition of 1872 they were found in much greater abundance 

 than on the present one. It was estimated that on the Expedition of 

 1872 not less than two thousand were killed, and yet not a man nor 

 an animal was bitten by them. This shows how little danger there 

 really is from them, even when numerous. Man is a far more fatal 

 enemy to the snake than the snake is to man. I was surprised to 

 find how late in the season they are found abroad, as we met with 

 them quite frequently after several severe frosts had occurred. Dur- 

 ing July two pairs were found in coitu, indicating the season at which 

 they pair. 



6. Bascanion flaviventris B. & G. 



Two specimens were taken in the valley of the Yellowstone, near 

 Camp Thorne, and only two or three others were seen. 



7. Pityophis bellona B. & G. 



A single specimen taken at the mouth of Custer's Creek, Sept. 1st, 

 was the only one seen. 



8. Heterodon nasicus B. & G. 



A specimen was taken near the head of Heart River, and another 

 in the valley of the Yellowstone; one or two others were observed. 



9» Eutsenia proxima B. & G. 



Not common. Less than half a dozen representatives of the genus 

 Eutcenia seen on the whole trip. 



