Article III. — The North American Sj>ccies of Diaptomus. 



By Frederick William Schacht. 



INTRODUCTION. 



The first published reference to that group of genera of 

 Entomostraca now known under the family name of Centro- 

 pagidce is contained in 0. F. Muller's "Entomostraca seu 

 Insecta testacea quae in aquis Daniae et Norvegiae reperit," 

 etc., published at Frankfort-on-the-Main in 1785, in which 



The following paper was prepared in the course of 

 undergraduate study in the Zoological Department of the 

 University of Illinois, and was accepted by the Faculty 

 of the University June 7, 1897, as a thesis for the degree 

 of Bachelor of Science in Zoology. 



187 7 ana tnose oi marsii in iodi. » »niyjc a^x^i^a v ^. 

 kentuckyensis) named by Chambers in 1881 is so imperfectly 

 described that its recognition is apparently impossible. Since 

 the publication of Underwood's " List of the described Species 

 of Fresh- water Crustacea from America North of Mexico" 

 ('86) the number of recognized North American species of 

 Diaptomus has increased from five to twenty-three. 



The literature of the genus previous to 1889 was widely 

 scattered and the synonymy greatly complicated, but the 

 comprehensive and careful "Revision" published in that 

 year by de Guerne and Richard ('89b) has had the effect 

 greatly to facilitate its study. The most important recent 

 European contributions to a knowledge of the Centropagidce 



9? 



