56 NINETEENTH REPORT. 



which lay their eggs in the water and pass their larval life there, but as 

 adults live some distance from the water, and (3) the species (this series 

 includes but a single species, Plethodon erythronotus ) which lays its 

 eggs and passes both larval and adult life in damp Avoods, away from 

 water but in a moist habitat. These three series with their associated 

 species include all of the amphibians and reptiles of the Douglas Lake 

 region except one, Nectiirus maculosus, the only member of the fauna 

 considered, which passes its entire life in the water. In the following 

 paragraphs the interrelations of the amphibian and reptilian species are 

 considered with reference to the groups outlined. 



Series 1. Preferred habitat of adults, szoamp; habitat of amphibian 

 larvae, aqtiatic. 



AMPHIBIA. 



Primary species Secondary species 



Diemictylus viridescens None 



Rana pipiens 

 Rana clamitans 

 Rana catesbeana 



ASSOCIATED REPTILIA. 



Primary species Secondary species 



Natrix sipedon Chrysemys cinerea 



Thamnophis sauritus Chelydra serpentina 



Thamnoiihis sirtalis 



Series 1 includes tlio.se species wliich frequent tlic swampy lowland of 

 the region, although some of them at least often stray into other asso- 

 ciations. The primary amphibian species of this group require still 

 water with more or less vegetation for spawning grounds and during 

 their larval stages. The larvae of Diemictylus viridescens spend one 

 summer in this habitat (Hay, 1892, p. i55), as do the tadpoles of Rana 

 pipens (Ruthven, Thompson and Thompson, 1912, p. 51). The tadpoles 

 of Rana clamitans and Rana catesbeana are dependent upon this habitat 

 for a longer time, spending two or three years in the water before trans- 

 forming (Dickerson, 1905, p. 20 1). The newt also returns to this 

 habitat after the second or third year and remains there as an adult 

 aquatic form. This (Hiiet water habitat is required by these species not 

 only because the decaying vegetable and animal matter wliicli forms a 

 considerable part of tlie food of their tadpoles and larvae is more fre- 

 quently deposited in still water than in moving water, but also because 



