238 Illinois State Laboratory of Natural History. 



Since there are only two species of Limnocalanus known, 

 the key is naturally very simple, and only the most striking 

 differences arc used. 



KEY TO THE SPECIES OF LIMNOCALANUS. 



Based on the Characters of the Female. 



1 (2). Hook-like process at inner apical angle of second 



segment of outer ramus of fifth leg armed for the entire 

 length of both margins with fine symmetrical teeth. 

 Outer apical angle of same segment armed with a 

 stout serrate spine. Second basal segment without 

 plumose seta at outer apical angle. macrurus. 



2 (1). Hook-like process at inner apical angle of second 



segment of outer ramus of fifth leg armed on the en- 

 tire inner margin with large teeth and on the outer 

 margin with a few line ones". Outer apical angle of 

 same segment without spine. Second basal segment 

 without plumose seta at outer apical angle. 



sinensis. 



Based on the Characters of the Male. 



1 (2). Right outer ramus of fifth legs 3-segmented (third 



segment indistinct). Hook-like process of second seg- 

 ment of this ramus simply and hut slightly curved ; 

 provided with hyaline plate. Inner rami alike. 



macrurus. 



2 (1). Right outer ramus of fifth legs clearly 2-segmented. 



Hook-like process of second segment of this ramus 

 somewhat sinuously curved. Inner rami unlike. 



sinensis. 



Limnocalanus macrurus Sars. 



Limnocalanus macrurus. Sars. '62, p. '22V>. 

 Limnocalanus macrurus, Forbes. ! 82a, p. 049. 

 Centropages grlmaldii, de Guerne, "SO. p. 276. 



Limnocalanus macrurus, Nordqvist, *S8, p. 31. PI. I., Fig. 9-11; PJ. 

 II., Fig. 1-5; Pi. III.. Fig. 1-1. 



-In de Guerue and Richard's "Revision," Fig. 5a in the description of Plate IV. 

 should be Fig. 15a. 



