462 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49. 



Wahsatch Mountains in Utah. This is undoubtedly very close to 

 tyrelli. The main points of difference as stated in the original de- 

 scription were as follows: 



1. The spines of the first basal segments of the female fifth foot are 

 large in coloradensis, small in tyreUi. 



2. The endopodite of the female fifth foot is shorter than the first 

 segment of the exopodite in coloradervsis , but longer in tyrelli. 



3. In the male fifth foot the distal margin of the first segment of 

 the right exopodite has two hyaline processes in coloradensis, one in 

 tyrelli. 



4. The lateral spine of the second segment of the exopodite of the 

 male fifth foot is strongly curved in coloradensis, but nearly straight 

 in tyrelli. 



5. The second segment of the exopodite of the male fifth foot has 

 a blmit spine on the dorsal surface in coloradensis, but none in tyreUi. 



6. The right endopodite of the male fifth foot is nearly as long as 

 the first segment of the exopodite in coloradensis, but much shorter 

 in tyrelli. 



7. The left endopodite of the male fifth foot is much stouter m 

 coloradensis than in tyrelli. 



A careful reexamination of the available material shows that these 

 points hold good except the sixth and that the endopodite of the 

 fifth foot in the female in some specimens equals in length the first 

 segment of the exopodite. To these may be added that the second 

 segment of the right exopodite of the fifth foot of the male in colora- 

 densis is nearly straight, while in tyrelli it is strongly curved and 

 somewhat shorter and stouter. A minor point may also be men- 

 tioned that apparently in coloradensis the lateral spine of the second 

 segment of the exopodite of the right fifth foot of the male turns 

 down — that is, toward the distal end of the segment — while in tyreUi 

 it turns toward the proximal end of the segment. 



The distinctness of coloradensis then seems assured, and further 

 study of the related forms may make it best to separate others from 

 tyrelli. 



D. priUlofensis Juday and Muttkowski, must, without doubt, be 

 considered identical with D. tyrelli. 



LITERATUHE CITED. 



De Guerne, J., and Richard, J. 1889. Revision de Calanides d'eau douce. M^m. 

 Soc. Zool. de France, vol. 2. 



Hbrrick, C. L., and Turner, C. H. 1895. Synopsis of the Entomostraca of Minne- 

 sota. Geol. and Nat. Hist. Survey Minn., 2nd Report State Zoologist. 



Juday, C, and Muttkowski, R. A. 1915. Entomostraca from St. Paul Island, 

 Alaska. Bull. Wisconsin Nat. ffist. Soc, vol. 13, No. 1, pp. 23-31. 



Marsh, C. D. 1907. A Revision of the North American Species of Diaptomus. 

 Trans. Wisconsin Acad., vol. 15, pp. 381-516. 



PoppE, S. A. 1888. Diagnoses de deux esp^ces nouvelles du genre Diaptomus West- 

 wood. Bull. Soc. Zool. France, vol. 13, p. 159. 



ScHACHT, F. W. 1897. The North American Species of Diaptomus. Bull. IlUnoifl 

 State Lab. Nat. Hist., vol. 5, art. 3. 



