REPORT ON THE FRESH-WATER OSTRACX)DA OF TllF 

 UNriED STATES NATIONAL MUSEUM, INCLUI)I\(i \ 

 REVISION OF THE SUBFAMILIES AND (JEXFJJV OF 

 THE FAMILY CYPRIDID^E. 



B}^ Richard W. Sharpe, 



Instnictor in Biologi/, WHmettc, TlUnois. 



INTRODUCTION. 



The following- report presents in part the results of ii study of the 

 fresh-water Ostracoda belonging to the United States National Museum. 

 The g-reater portion of the material was collected from quite widely 

 separated regions. Places as remote from one another as New Jersey 

 and California on the one hand, and Oregon and Mexico on the other, 

 are represented. 



The material has been collected by friends of the U. S. National 

 Museum, somewhat cursorily and in small quantities. Dr. E. Palmer, 

 Dr. Alfredo Duges, Mr. E.' W. Berry, and Prof. H. I. Suuth, are 

 among- those who have contributed. 



So much confusion and error has arisen on account of the genus 

 name Ot/prmotus, that I shall here use it as a subgeneric name under 

 the genus Cypris. The attempt has been made to distinguish the 

 genus Cyprinotus from the genus Cypris by means of the method of 

 propagation and the presence or absence of tubercles on the right 

 shell margin. Cyprinotus was distinguished from Cypris by being 

 sexual — while Cypris parthenogenetic — also by possessing a row of 

 tubercles on the right shell margin, which Cyprix lacked. 



As regards the method of propagation, it is undeniably the case that 

 it is not always a genus character among the Ostracoda. For instance. 

 Ilyocypris gihha Rahmdohr is not represented by mahvs. wliile f I y< 'cy- 

 pris lacustris Kaufmann is propagated sexutdly. 



Indeed, European forms of Cy2Jris clmata Baird are parthenoge- 

 netic, while African forms of the same species are sexual. Further- 

 more, Cypris testudinaria Sharpe is sexual, a character Avhich might 

 have allied it with Cyprinotus, but it is entirely without tubercles on 

 the shell margins. In fact, it seems that this species In-eaks down 

 any possible bai-rier between Cypris and Cyprinoim, indicating that 



Proceedings U. S. National Museum, Vol. XXVI— No. 1347. 



