288 



UNIVERSITY OF COLORADO STUDIES 



102 (126) Antennae very long (23-25 segments), often reaching to the end of the 

 body. In males the right antenna is enlarged and geniculate. 5th feet 

 of female similar and small; of male the right one is much larger. Female 



carries a single egg-sac Family Centropagidae 



Only one genus represented in Colorado records. Antennae 25- 

 segmented. Right sth foot of male ends in a more or less sickle-shaped hook. 

 Endopodites of swimming feet 2-3-3-3-segmented. Genus Diaplomus 



The key to the genus Diaptomus is based upon the characters of the adult male. DetermiDations are 

 not easily made from female specimens, but they may be without difficulty referred to the proper males in the 



collection. 



The various species of this genus form an important part 

 of the Copepod fauna of fresh waters throughout the world. 

 Many of them are conspicuous on account of their bright 

 colors. The individual species are extremely restricted in their 

 distribution. Of the 36 species known to occur in North 

 America, not one extends beyond the bounds of the continent 

 and most of them have a very much more restricted range 

 than that. Of the 13 species that have been found in Colo- 

 rado, nearly all have a range not extending beyond the Rocky 

 Mountain region. The genus is one in which success has been 

 attained by means of many species, each with a limited range. 



103 (120, 123) Antepenultimate segment of 



right antenna with terminal process 104 



(in) Terminal process straight 105 



(108) Terminal process shorter than penultimate segment. . . . 106 



(107) Terminal process much shorter than penultimate segment and 



tapered at end. Endopodite of right 5th foot shorter than first segment of 



exopodite. Length: male, 0.9; female, 0.93 mm. Diaptomus judayiMa.ish. 



Twin Lakes; 9,200 ft. Only record for this species. 



Fig. 61. — Nauplius larva of a Copepod. 

 (After Groben from Lang's Comparative 

 Anatomy.) 



104 



106 



( 4 --Ofrau* »?/"«' 



Fig. 62. — Diaptomus judayi. a, last three segments of male right antenna; b, abdomen of female: 

 Cf 5th foot of female; d, 5th feet of male. (After Marsh.) 



