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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 05. 



either in northern latitudes or in higher elevations of more southern 

 regions. 



The lakes on the plains, as previously mentioned, have several 

 species in common with those in the mountains, but they lack those 

 just mentioned as belonging especially to the mountains. In addition 

 they have several species which do not extend into the mountains at 

 all, but are common forms in lowland lakes. Conspicuous among 

 these are four species of Diaptomus, which, both on account of their 

 size and their numbers, constitute an important part of the entomos- 

 tracan fauna. Diavtomus claviceps and D. washingtonensis are found 

 in abundance in five lakes, while D. siciloides and D. alhuquerqitensis 

 are plenty in certain others. It would be of interest to have collec- 

 tions from other lakes in this region to determine whether these four 

 species are commonly associated in these two groups, and if possible 

 to determine the underlying conditions. Daphnia pulex is commonly 

 present in these lakes, but D. longispina was not collected, the findings 

 again agreeing with common conditions in the plains portion of the 

 State. The other species do not call for special comment. 



In regard to amount of entomostracan life, there is some advantage, 

 though not great, with the lakes on the plains. The mountain lakes 

 are by no means scant in species or in individuals, nor is the size of 

 the individuals less than in the warmer lakes. I have made no 

 attempt to compare in detail the fauna of the different lakes. Points 

 of interest might appear in such a study, but it appears that the great- 

 est interest of these collections is their relation to altitudinal zonation 

 and their bearing upon this problem as it has been studied at other 

 points in the same general region. 



