1883.] NATURAL SCIENCES OF PHILADELPHIA 33 



northwards of the ranges of Crotalas molossus and Stenostoma 

 dulce. No. 2. The extension northwards of the ranges of Diado- 

 phis regalis, Grotalus lepidus and Eolhrookia texana. No. 4. The 

 extension to the Rocky Mountains of the range of Spea hdmmondi. 

 No. 6. The discovery of a new Scaphiopus in the Great Basin 

 district ; and of the southern extension of Eana pretiosa into the 

 same. No. T. The discovery that the Northern Pacific fauna 

 extends east to the Rocliy Mountains. This fauna is especially 

 represented by Bascanium vetustum, Bana preMosa and Bufo 

 columbiensis. No. 8. The fact that the Great Basin district of the 

 Sonoran fauna extends north to the southern slope of the Rockj'^ 

 Mountains in Idaho, where are found several of its species. These 

 are Bhrynosoma platyrhinum, Grotaphytus wislizeni, and Uta 

 stansburiana. No. 9. The discovery that the same fauna extends 

 north along the eastern slope of the Sierra Nevada to the begin- 

 ning of Surprise Valley, California. No. 10. The determination 

 that the Northern Pacific fauna extends from Surprise Valley, 

 eastern California, northwards as ftir as my explorations have 

 extended, viz., to Silver Lake and Klamath Lakes. No. 15. The 

 determination of a wide southern range for Spea hammondi and 

 Bufo columbiensis, and northern range for Verticaria hyperythra. 



These results indicate that the Pacific region has a much greater 

 extension eastward than it has been supposed to have, but which 

 was foreshadowed in my paper on the Zoology of Montana, 

 published in 1879.^ They also indicate that it must be divided 

 into three districts. These I call the Idaho, the Willamet, and 

 the South Californian districts. The first is characterized by the 

 absence of Gerrhonotus and Gynops and of certain species of 

 Amblystoma. The South Californian is characterized by the 

 presence of Hypsiglena and Bhinochihis, and absence of Amblys- 

 toma. It is allied to the Sonoran region, to whicli it is adjacent. 



As regards the relation which the Sonoran region as a whole 

 bears^to the Nearctic and Neotropical realms, some remarl<s may 

 be in place here. It is a question with some naturalists to which 

 of the two it should be referred, and some would exclude it from 

 the Nearctic without fully determining its relations to the Neo- 

 tropical realm. 



There can, however, be no doubt that it lacks all the peculiar 



^ American- Naturalist, p. 435. 



