Amphibia 113 



house's Toad (B. woodhousei of Girard), which is widely distributed 

 east and west, from Lamar to Grand Junction. If the median 

 crests diverge posteriorly, and there is a short diagonal crest at 

 each posterior inner corner, where the transverse crests begin, we 

 recognize the American Toad (Bufo americanus of Le Conte). 

 It apparently belongs only to the region east of the mountains, 

 having been found at Boulder, Denver, Brighton and Julesburg. 

 Possibly it has spread into this region since the advent of man, 

 coming from the east. The remaining species, the handsomely 

 marked Say's Toad (Bufo cognatus of Say), has the bony crests 

 diverging, with no projecting small crests at the elbows or corners. 

 It belongs to the eastern plains; Brighton, Wray, Julesburg, 

 Greeley, and has also been found in Costilla County. It was one 

 of the discoveries of Long's Expedition. 



Our Hylidae, although called "tree frogs", live mainly or 

 entirely on the ground. It is in the moist tropics that their rela- 

 tives are so abundant on the trees, and often colored green like 

 the foliage. I n the Three-lined Frog (Pseudacris triseriata of Wied) 

 the toes have scarcely any webbing, and the skin is smooth. It is 

 a small frog, with very variable markings, and extends from the 

 plains high into the mountains. The Cricket Frog (Acris gryllus 

 of Le Conte), usually having oblique dark spots on the back, just 

 enters Colorado from the east, having been found by Dr. M. M. 

 Ellis at Wray. The Arizona Tree-frog (Hyla arenicolor of Cope), 

 with distinct terminal discs on the toes, is a southern species which 

 has been taken by Beardsley in Las Animas County. 



Our only native typical frog (Rana pipiens) is common every- 

 where, and needs no description. The Bullfrog (Rana catesbeiana) 

 has been introduced into ponds in the South Platte Valley, but 

 Ellis and Henderson state (191 5) that it does not appear to thrive. 



