622 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



the total, 11 J, reaching from the nodus to just proximal to the 

 seventh postnodal. The spaces of the hind wing measure 5, 2§, 3J; 

 the total, lOf, reaching from the nodus to just distal to the sixth 

 postnodal. In the 25 wings of this species tabulated as to various 

 characters, the stalks of the sectors of the arculus were studied but 

 not tabulated. In 2 front wings and 2 hind wings only short stalks 

 were present, but in all other cases the stalk of the sectors was long 

 or very long — the longest detected in all the wings of the various 

 species tabulated. It is possible that this character should have 

 been added to those tabulated. 



Described from 16 males and 6 females, Cashew Creek, Tumatu- 

 mari, British Guiana, February 8, 9, and 11, 1912, and 4 males, 1 

 female, small creek just above Potaro Landing, British Guiana, 

 February 10, 1912. Type, a male, and allotype, a female from 

 Tumatumari, February 8, in my collection. Named for Dr. Philip 

 P. Calvert, whose leadership in systematic American Odonatology 

 for 20 years has won the gratitude and admiration of all students of 

 dragonflies. 



Paratypes. — Cat. No. 19214, U.S.N.M. A male and a female from 

 Tumatumari, British Guiana, February 9, 1912. 



Cashew Creek is a small sluggish stream, during low-water stage 

 2 to 6 feet wide, flowing in a mud bed through woods. During low- 

 water stage it is the first flowing water entering Potaro River above 

 Tumatumari on the same side of the river. Just above Potaro Land- 

 ing is a similar smaller and more shaded stream. In shade this species 

 is all but invisible on the wing. As the males came out in the sun- 

 light, to flutter almost motionless near the water's surface, the red 

 thoracic spots would suddenly appear like tiny flames to attract the 

 attention of the collector. Usually some time elapsed before the rest 

 of the insect could be discerned and its position determined. When 

 they moved the direction of flight could rarely be seen. After some 

 experience with them I became more adept in locating them over the 

 water and could more quickly distinguish the various parts of the 

 body. But a hurried collector, and one unappreciative of the 

 phantomlike character of some of the slender, shade-frequenting 

 tropical agrionines, might have passed up and down the creek many 

 times without detecting the presence of this beautiful and graceful 

 insect. Twice in Trinidad at different small streams I caught the 

 flame-flash of the red-spotted thorax of this or a similar species, but 

 in neither case was I able to obtain a second glimpse of the insect 

 itself. 



The female oviposits in submerged leaves, the apex of the abdomen 

 brought almost directly beneath the wing bases, the first 4 segments 

 held aloft and the last 6 segments directed almost vertically down- 

 ward, in a position suggestive of an ovipositing ichneumon-fly, 

 Thalessa. 



