562 PROCEEDINGS OF THE NATIONAL MUSEUM. you 52. 



color pattern in four other females. Figures 272-278 show the 

 structural details of this species. 



Measurements are as follows: Male, abdomen, 37-40 mm.; hind 

 wing, 31-32; female, abdomen, 36-39 mm.; hind wing, 30-32.5 



Because of previous studies of the postanal cells in Gomplius rela- 

 tive to their use in grouping the species into subgenera, I give here 

 the forms they take in this species. The fifty males were examined 

 and 24 = A (fig. 313), 7 = B; 2 = C; 9 = D; 2 = H. Each of the other 

 figures represented one specimen each, and one deformed wing was 

 not figured. The females were not examined. 



GOMPHUS DONNERI, new species. 



One of the interesting surprises among the Odonata of beautiful 

 Donner Lake was a species of Gomplius. This genus, which is asso- 

 ciated in one's mind with the warm sluggish streams of the lowlands, 

 was represented here at an elevation of almost 5,000 feet by numerous 

 specimens of an almost black species, a close relative of its near 

 lowland neighbor GompJius sohrinus. 



I first saw a specimen of this species on July 23, while I was collect- 

 ing OpTiiogomplius morrisoni near the outlet of the lake, but after 

 several attempts failed to catch him. A fuller exploration of the 

 lake revealed the sand beaches around the west end, a different shore 

 from the cobble and pebble beaches of the east end, and on these sandy 

 beaches of the west end, this new Gomplius. During two days' collect- 

 ing about 80 males and 2 females were taken, and after extended 

 search several broken exuviae were found around driftwood and 

 boulders along the shore. Because of the very evident scarcity of 

 females the species was probably past its prime, though still abundant. 

 I was not fortunate enough to observe it emerging, copulating, or 

 ovipositing. It passed most of its time resting on the bare beach or 

 some low stone, though it occasionally lit on a low bush or weed. 

 Along the west shore, where the sandy beach was continuous, it was 

 the only species found, but along the west end of the north shore, 

 where sandy stretches alternated with gravel and rock, it was asso- 

 ciated with OpTiiogomplius morrisoni, Enallagma cyaihigerum, and 

 Argia vivida. 



Length of abdomen: Male, 37 mm. (35-38); female, 36 and 37.5. 

 Length of hind wings: Male, 30 mm. (28-32.5); female, 31 and 32. 

 Length of pterostigma of front wing: Male, 2.8 mm. (2.5-3.2); 

 female, 3. 



Type.— C&t. No. 20815,. U.S.N.M. A male from Donner Lake, 

 Nevada County, Cahfornia, July 23, 1914. 



Allotype. — Cat. No. 20815, U.S.N.M. A female from Donner Lake, 

 Nevada County, California, July 23, 1914. 



