2 PROCEEDINGS OF THE NATIONAL. MUSEUM. vol.65. 



quadrangula, and Diaptomus washingtonensis. The finding of Diap- 

 tomus washingtonensis here, at the eastern base of the Rocky Moun- 

 tains, is of interest. The species was described by Marsh from 

 material collected at Walla Walla, Washington, and its occurrence 

 here is a long extension of range for a species of this genus, which is 

 one composed of many species, most of which have rather limited 

 range. It makes up an important part of the fauna of six lakes on 

 the plains, but is not found in any of those in the mountains. There 

 seems to be no doubt about the identification, as it bears all the 

 marks by which Doctor Marsh distinguished it from D. signicanda, and 

 agrees well with his figures and descriptions of material from the 

 State of Washington. 



The State of Colorado includes an area that has a far greater 

 biological significance than might be expected of a mere political 

 area. vSituated as it is, astride the Continental Divide, it includes 

 the highest portion of the Rockies, is the meeting place of eastern 

 and western faunas, includes lowland areas of both the Great Plains 

 and the Great Basin, and in its higher areas includes southern exten- 

 sions of high northern faunas. It is thus a meeting place for faunas 

 which under ordinary conditions are separated by hundreds of miles. 

 The vState includes portions of five life zones — Upper Sonoran, 

 Transition, Canadian, Hudsonian, and Arctic-alpine. The collections 

 of Shantz are of interest because they include a section through all 

 of these zones with the very different climatic conditions prevaihng 

 at the extremes. It was with these conditions in mind that Shantz 

 selected these lakes for study, as clearly indicated in the opening 

 paragraph of his paper: 



Here, within a few miles of each other, are two groups of lakes representing 

 quite different tj^pes, the alpine and those of the plains. The alpine lakes lie 

 far up on the mountains, * * * with typical alpine surroundings. The 

 plains lakes lie on the western edge of the Great Plains, * * * with condi- 

 tions which are in no wise alpine. They are lowland lakes. 



The species in these collections take on their greatest significance 

 when considered in connection with the above facts, especially when 

 considered in connection with my own collections from the Tolland 

 region. It is hoped that the frequent reference to my own collections 

 are made in such a way as to emphasize the importance of those 

 made by wShantz, which, though made several years before I had done 

 any collecting, unfortunately, were not determined, and so were 

 deprived of the priority of notice to which they were entitled. Though 

 they do not include by any means as many lakes as do mine, had 

 they been studied soon after they were made they would have antici- 

 pated many of the facts presented in my earlier papers. 



The species in these collections, just as did those from my own 

 collections, fall into three natural groups, (1) 13 species found on the 

 plains but not extending into the mountains, (2) 9 species found only 



