Ridgway.] 304 [February 18, 



among the suspended particles, which come together and soon sub- 

 side, leaving the saline liquid clear. The precipitation of suspended 

 clays is very rapid when a strong solution of salt is made use of. 



The Lower Wabash Valley, Considered in its Relation 

 to the Faunal Districts of the Eastern Region of 

 North America; with a Synopsis of its Avian Fauna. 

 By Robert Ridgway. 



Part I. — General Preliminary ; Relation of the Lower Wabash 

 Valley to the Faunal Districts of the Eastern Region of North Amer- 

 ica ; local characteristics of its Avian Fauna. 



The present paper is intended as a step toward supplying an im- 

 portant deficiency in our knowledge of the geographical distribution 

 of the birds of the Mississippi Valley. In this undertaking encour- 

 agement is given by the success of Mr. Allen's treatment of the avi- 

 fauna of adjoining portions, 1 as well as by the hope that a gap exist- 

 ing between the local lists of the Atlantic States and those States 

 along the western border of the Mississippi may be filled. 



It is the purpose to here present a condensed review of the birds 

 belonging to a section of the country which is of great interest to 

 ornithologists, from the fact that it is as yet comparatively a terra in- 

 cognita as regards our knowledge of the details of its bird life. No 

 portion of the Eastern Region of North America presents a richer 

 field for ornithological research. This arises from its unusually 

 favorable physical conditions and consequent diversity of natural 

 productions, for no portion of the continent is more replete with 

 both animal and vegetable life. The wild regions of the Far 

 West have been almost exhausted of novelties in this line through 

 the agency of numerous Government Surveys which have traversed 

 them in every direction, while the States bordering the Atlantic 

 have been pretty thoroughly worked up by the zealous efforts of 



1 The titles of Mr. Allen's papers on the birds of localities in the Mississippi Val- 

 ley, are the following : — 



I. Notes on the Birds observed in Western Iowa (July 1 to Sept. 20 — 108 spe- 

 cies), Northern Illinois (June — 94 species) and Richmond, Wayne Co., Indiana 

 (June — 72 species). Mem. Bost. Soc. Nat. Hist., Vol. I, pp. 491 — 526. 



II. List of Birds observed in Leavenworth, Kansas, from May 2 to May 11, and 

 at Topeka, Kansas, from May 11 to May 24, 1871 ; with annotations. Bulletin of 

 the Mus. Comp. Zool., Cambridge, Mass., Vol. hi, No. 6, July, 1872, pp. 122-131. 

 (121 species.) 



