102 



PliOCEEDlNaS OF THE XATIONAL MVBEUM. 



VOL. 40. 



These specimens agree well with the description of Forbes except in 

 one particuhir which seems worthy of comment. He figures the ante- 

 penultimate segment of the male right antenna with a straiglit process, 

 though in his description he does not state whether it is straight or 

 curved. Marsh/ in his key, interprets it as a straight process. In 

 my material this process is always decidedly curved, 

 though it varies considerably in length. The condi- 

 tions represented in figure 7 show the two extremes 

 between which most specimens lie. Figure 8 is a copy 

 of Forbes's drawing from the Yellowstone material. 



DIAPTOMUS SHOSHONE Forbes. 



This is the most common Copepod in the mountains 

 west of Denver, where I have collected it at elevations 

 from 9,575 to 12,188 feet, but mostly in lakes above 

 11,000 feet. It ranges along the highest parts of the 

 Rocky Mountain range, havmg been collected by 

 Forbes in the Yellowstone region and by Ward^ at 

 Pikes Peak. Though Forbes does not figure the female 

 abdomen, he describes it as being asym- 

 metrical. Marsh 2 states that in the 

 Pikes Peak material he does not find 

 this to be the case as does also Schacht^ who studied 

 Forbes's collections. Marsh's figures, however, draAvn, 

 I suppose, from the Pikes Peak material, show the first 

 segment of the female abdomen as distinctly asymmet- 

 rical. In my collections this asymmetrical condition 

 prevails, as illustrated in figure 9. Marsh mentions the 

 fact that he finds the endopodite of the female fifth 

 foot and of the left male fifth foot to be indistinctly two- 

 segmented. This is also the case with my specimens. 

 It may also be worthy of note that in some lakes the 

 appendage of the antepenidtimate segment of the male 

 right antenna is much longer than is the general rule, 

 reaching well beyond the end of the ultimate segment. 



Fig. 9.— Diaptomus 

 suosHONE. Female 



ABDOMEN. X 50. 



DIAPTOMUS LEPTOPUS, var. PISCINAE Forbes. 



Fig. 10.— Diaptomus 



LEPTOPUS, var. pis- 

 cinae. Terminal 

 SEGMENTS OF MALE 

 RIGHT ANTENNA. 

 X 1S8. 



This is the most common representative of the genus 

 in the lakes of the ToUand region below 11,000 feet. 

 In all my specimens the hyaline lamella of the ante- 

 pemdtimatc segment of the male right antenna is expanded at the 

 distal end into a very decided angle, as seen in figure 10. So far 

 as I know, this has not been mentioned or figm-ed for material from 

 other localities. 



1 C. Dwight Marsh, A revision of the genus Diaptomus. Trans. Wis. Acad., vol. 15, pt. 2, 1907, pp. 3S1-486. 



2 C. Dwight Marsh, Report on the Copepoda, In A biological reconnaissance of some elevated lakes in the 

 Sierras and the Rockies, by Henry B. Ward. Studies from Zool. Lab. Univ. of Nebr., vol. 3, 1904, pp. 

 146-149. 



» F. W. Schacht, The North American species oV Diaptomus. Bull. 111. State Lab. Nat. Hist., vol. 5, art. 

 3, 1897. 



