FOSSIL FRESHWATER MOLLUSKS 

 FROM OREGON 



INTRODUCTION 



The University of Oregon possesses a collection of fresh-water 

 fossil mollusca which was assembled by the pioneer geologist of 

 the state, Prof. Thomas Condon. "While his interest was chiefly 

 centered in the vertebrates, he collected a considerable amount of 

 material in other groups as well. The writer has already reported 

 upon the collection of fossil land shells made by him, 1 and it is 

 through the courtesy of Dr. Earl L. Packard of the Department 

 of Geology of the University that the results of a study of the 

 freshwater forms is here presented. 



The collection contains 21 lots of material, chiefly from sup- 

 posed Pliocene deposits in the vicinity of Warner Lake in the 

 eastern part of the state. One lot, however, appears to be of 

 Eocene age and three have been recorded from the Pleistocene. It 

 must be explained, however, that the last age determination was 

 made with grave doubt as to its correctness because we know 

 nothing of the stratigraphy of the deposits involved. The basis 

 was solely the presence of the genus Carinifex in the material. It 

 may have been accidentally excluded from the other lots since each 

 one consists merely of a block of the material as it existed in place. 

 No attempt was made in the collecting to secure a full representa- 

 tion of the species at any locality and as a consequence some of the 

 most remarkable forms are represented only by fragments. Un- 

 doubtedly many more, not here recorded, exist at the various 

 places and the field is one which offers great possibilities to the 

 trained collector of fossil shells. 



One notable feature connected with every locality is the absence 

 therefrom of any species of the genera Lymnaea and Physa. 

 Whether this is merely due to the manner in which the collections 

 were made or whether these widespread groups actually did not 

 exist in those ancient Oregon lakes can of course not be stated until 

 further field work is done. The absence of all UnionicUe is also 

 noteworthy. 



1 Hnna, G. D. Univ. Or*. Pub.. Vol. 1. No. . pp. 1-8. pi. 1. 1920. 



