THE POLISTES ATERRIMA. 599 



sharp and firm, without needing either pressure or excavation to 

 make them so. 



It is much to be regretted that in England there is no repre- 

 sentative of this interesting group of insects by which the above- 

 mentioned problem might be solved. We might then know 

 whether males and females belong to the same brood, are nur- 

 tured in the same cells, and are of the same size. We might 

 learn whether or not the males are bred in separate establish- 

 ments, divided from the other sex like dioecious plants. As it is, 

 however, we are in ignorance respecting these points, and no one 

 resident in tropical countries seems to have the energy to con- 

 duct a series of experiments which would involve expenditure 

 of time and labor. Travelers and residents in tropical countries 

 are often admirable collectors, but, with few exceptions, are poor 

 observers, except of facts that pass immediately under their ob- 

 servation. They make valuable collections, and record many 

 useful isolated facts ; but, unfortunately, they seldom appear able 

 to carry on a series of experiments that would occupy several 

 successive years, and thus we lose much valuable as well as in- 

 teresting knowledge, and waste much time in trying to discover 

 by inference that which we ought to know from observation. 



The last point which will be noticed in connection with this 

 remarkable cell group is that it is perfectly protected from rain. 

 Slight and delicate as is the structure, appearing scarcely thicker 

 than the silver paper with which engravings are guarded, it may 

 be deluged with water without being wetted. Over the whole 

 of the cells the insect contrives to lay a thick coat of some var- 

 nish-like substance, which at the same time gives the exterior of 

 the cells a polish, binds them more firmly together, and renders 

 them water-proof. The varnish is nearly transparent, but has a 

 blackish hue, which gives to the whole cell group a uniformity 

 of aspect which would be wanting if the protecting substance 

 were itself colorless. 



The insect is, at first sight, black in color, as is expressed by 

 its specific title. A clear examination in a more favorable light 

 shows -that the true color is a green so deep as to appear black, 

 but having a perceptible bronze gloss in certain lights. The 

 wings are equally sombre in aspect, looking as if they had been 

 held above the flame of a badly -trimmed lamp, and received all 

 the soot upon their translucent membranes. Indeed, their pecul- 

 iar color can only be expressed by the word "smoky." 



