60 NINETEENTH REPORT. 



pond was the favorite habitat of young woodfrogs and toads during the 

 last of July and the first of August. On Lancaster Lake in certain 

 places the woods came almost to the water's edge and the upper beach 

 zone was wanting. In the vicinity of waterlily associations on this lake 

 the beach margin of the forest served as a transitional habitat for numer- 

 ous young woodfrogs and toads. 



The secondary amphibians of series 2 include those species which 

 were not taken in large numbers, the rare or scarce species of amphibians 

 of the Douglas Lake region. 



The reptilian species of series 2 are three snakes, to which the water- 

 snake, possibly should be added. The two species of Thamnophis fed 

 upon young toads and woodfrogs in the transitional habitats, especially 

 in the upper beach zone, Tliamnophis sirtalis being the more important 

 enemy of these amphibians because of its abundance and wide distribution 

 throughout the Douglas Lake region. The hognosed snake, Heterodon 

 platyrhinos, was found more frequently in the aspen association than in 

 the upper beach zone, the only habitat of the three habitats frequented 

 by this snake in the Douglas I>ake region (see tables) in which large 

 numbers of woodfrogs and toads were seen. The food of the hognosed 

 snake seems limited to toads and frogs, the snake having a preference for 

 toads (Ditmars, 1908, p. 382). Because of this choice of food the hog- 

 nosed snake is very definitely dependent upon two of the amphibians of 

 series 2. It is possible that the watersnake fed upon young toads and 

 woodfrogs in the upper beach zone occasionally as it was seen in that 

 habitat several times. 



Series 3. Habitat of adults, damp -woodland , second growth forest or 

 aspen; habitat of ampliihian larvae, damp, rotten leood. 



AMl'lIIHIA. 



Primary species 



Pletliodon ervthronotus 



ASSOCIATED REPTILIA. 



Primary species Secondary sjiecies 



Lampropeltis doliatus triangu- Storeria occipitomaculata 



lus Diadophis jjunctata 



Liopeltis vernalis 

 Eumeces quinquilineatus 

 Terrapene Carolina 



