19 (i8) 



20 (21) 



COPEPODA 



759 



Inner process of terminal segment of left exopcxlitc of male i.fth 

 foot digitiform, hyaline appendage on internal distal angle 

 of first segment of right exo{)odite ,0 



Lateral spine of second segment of right exopodite nearly straight 

 no blunt spine on posterior surLice of this se-gmenl. ' 



Diaptomui tyrtlli Vo\^\n: iSMM. 



Widely spread in the mountain lak.-s of the West. 

 Lenf^th of female. 1.2 mm. 

 Length of male, 1.15 mm. 



Fig. 1181. Fifth feet of male Diapiomui tyrtlli X lya 

 (Original.; 



21 (20) A second hyaline appendage on dorsal side of distal margin of tirst 



segment of right exopodite, lateral spine of second segment 

 of right exopodite strongly curved, and a blunt spine on 

 posterior surface of this segment. 



Diaptomus coloradoisis Marsh i()i i. 



In the Rocky Mountains in Colorado D. tyrclli is repiacctl by thi.s cio?<-Iy 

 allied species which is, apparently, the characteristic species of the moun- 

 tain lakes of Colorado. 



Length of female, 1.38 mm. 



Length of male, 1.32 mm. 



Fig. 1182. Vdlh ieetol male Diaptomus coloTodemis. X uo. (.Original.) 



22 (9) Antepenultimate segment of male riglu antenna with lateral lamella 



or terminal process ^ 



23 (26, 42) Antepenultimate segment of right antenna of male Nvith h.Nalino 



lamella 



