256 A YEAR OF COSTA RICAN NATURAL HISTORY 



male). The egg-laying habits of Palcsm7iema are unknown 

 and I stood in the mud for forty minutes keeping my eyes 

 fixed on the pair, in the hope that I would obtain some 

 information on this point. During this period they shifted 

 their position to five different leaves or twigs but gave no 

 sign of depositing eggs, so, fearing that I might lose them, 

 I caught them in my net. Experience had taught me that 

 the dragonflies which inhabit dark woods are very difficult 

 to keep in view, owing to the transparency of their wings 

 and the prevailing somber tint of their bodies. Often there 

 is, however, a small limited area of a lighter color and, if 

 one can keep his eye on that, he can follow the insect as it 

 flits from plant to plant, but even so the greatest attention 

 is necessary and I have often lost desirable insects. In this 

 Palcsmfiema the most conspicuous light area, but not the only 

 one, was formed by two small parts of the head — the labrum 

 (or upper lip) and the nasus — which were pale blue. A 

 species which I lost in this same piece of woods this day, 

 a Philogenia, had only one or two segments of the hind end 

 of the abdomen pale colored, like the whitish "bloom" 

 sometimes seen on a plum; all the rest of the body was dark 

 and the insect kept to the shadows so closely that it was 

 very difficult to see. 



Some writers, like Mr. E. B. Williamson, have suggested 

 that these more conspicuous pale areas on dark bodies of 

 dragonflies (not necessarily those confined to dark woods) 

 serve as recognition-marks to the other sex. 



I naturally looked for additional specimens of the new 

 genus and of the Palcemnema, but unsuccessfully, until the 

 increasing cloudiness warned me to seek shelter before the 

 beginning of the usual heavy afternoon rain. Search for 

 them was in vain on the following morning also, when I 

 attempted a grassy road which led up from the laguna Into 

 the woods, and which I finally gave up because of the deep 



