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115 



Contributions to a Knowledge of the Fresh-water Mollusca of 

 Kansas, IV, 



(Constituting the Fourth' Report of Progress of the Washburn College Biological 

 Survey of Kansas in the department of Fresh-water Mollusks.) 



BY R. ELLSWORTH CALL. 



^ 



In this contribution there are added to those already enumerated two 

 genera Pi*idiumAnd Ancylus and twelve species. Three species whose 

 names were previously given with doubt are now for the first time posi- 

 tively recorded from Kansas. Some of the new forms occur abundantly, 

 as is indicated by the numbers submitted. The discovery of Uniopusfulntus 

 in the Verdigris River places this species far to the westward of any hith- 

 erto recorded locality Davenport, Iowa, being the most western station 

 known hitherto. The minute corbiculid genus, Pitidium, also occurs for 

 the first time in the Survey collections, but is represented by few individuals 

 of the species abditum. The curious liinnseid genus Ancylus has also ap- 

 peared, and may be expected to occur in not inconsiderable numbers when 

 proper search is instituted. 



All portions of the State do not appear to be equally favorable to either 

 the development or the maintenance of molluscan life. In notes accom- 

 panying several parcels from south-central Kansas, Prof. Cragin mentions 

 certain features of a geologic character which the field conchologist always 

 recognizes as inimical to the development of the objects of his search. Of 

 Barber Co., he remarks as follows : " I found shells very scarce. The trib- 

 utaries of the Medicine River from the north have few shells, except in 

 the headwaters. Most of the tributary streams on the south side seem to 

 be entirely destitute of bivalves." It appears, from the notes submitted 

 by him, that the country is largely of a sandy and clayey formation, and 

 that limestone is absent almost totally, except in the form of the sulphate 

 i. e.< gypsum. In Barber and Harper counties the streams have a simi- 

 lar bed of sand, with the addition of considerable quantities of iron, prob- 

 ably in the form of the sesquioxide. Where either iron or gypsum occurs 

 in some abundance, experience has demonstrated that shell-life is reduced 

 to a minimum. It is highly desirable that such notes as these should ac- 

 company all collections, together with some statements as to the nature of 

 the bed where mollusks occur either abundantly or sparingly. Studies of 

 this sort are of inestimable value from a biologic standpoint, and by too 

 many students are utterly neglected. It is important, too, to observe care- 

 fully the conditions of springs in which mollusks occur. But few obser- 

 vations of this character are on record; yet many chalybeate, saline and 

 sulphuretted springs contain mollusks, and these always in number or in 

 size showing the biologic effects of the station. 



In this place only the usual record of species will now be made. Some 

 considerations on geographic distribution and synonymy have been included, 

 but full discussion of these questions must await returns from all portions 

 of the State, an(J receive proper treatment in a final report. 



