276 NATURAL HISTORY OF ARTHROPODS. 



oblique cross-nervule, and farther back by another, thus bounding an irregular cell. 

 The long abdomen is rather flat above, but convex beneath, with the margins parallel 

 in the male, and curved in the female. 



Thus far only a single species, S. lineata, have been found in the United States. 

 It is fuscous, with dusky hemely tra having fuscous veins ; the wings are white, also 

 veined with fuscous ; the tergum is pale brown, and has the margins of the connexi- 

 vura and the longitudinal sutures black, the transverse sutures are also often black, 

 and there is a more or less distinct pale line down the middle. This species varies 

 considerably in the depth of color and distinctness of the markings. It measures 

 rather more than one-third of an inch in length, and closely resembles the S. stag- 

 norum of Europe. Like the species just mentioned, it sometimes lives in the dirty 

 pools, among the duckweeds, Lenina, where it wanders about over the green algae and 

 slime floating on the surface ; the color of which it matches in the young stages. 



Having considered the forms which live in the water, or which pass much of their 

 time either on its surface or in the wet places adjacent to it, we reach those which are 

 terrestrial or essentially aerial. None of these have the antennas concealed, but 

 always prominently standing forth from the sides of the head. These, with the sub- 

 aquatic fonns which we have just considered, compose the great section Gymnocerata 

 of Fieber, just as the essentially aquatic assemblages belong to his preceding section 

 Cryptocerata. This last group he also designates as a subsectionj Aquatilia, from 

 the genuine aquatic habits of the forms, while he places our marsh-loving genera in 

 another subsection, Litoralia, and the teiTestrial insects, yet to be considered, in a 

 third subsection, which he calls GEODROMICA. 



The first group of this largest of the sections is the superfamily Reduvioidea. It 

 comprehends a vast assemblage of forms, which are easily grouped around some cen- 

 tral genus, forming in each case a natural family or subfamily, differing by easily 

 recognized features from all the others. At least fourteen of these groups, embracing 

 more than a thousand species, have already been made known. All the extremes of 

 figure are found here, from the longest and most attenuated, to the flattest and widest. 



All, however, agree in having a rostrum attached to the tip of the head, with the 

 basal joint bent, causing the rest of this organ to curve beneath, the tip usually im- 

 pinging upon the sternum and gliding upon a groove there. The eyes are j)rominent, 

 hemispherical, lateral, and placed before the base of the head ; when situated far back 

 they are succeeded by a constriction resembling a neck. 



Those which have an extremely slender body with thread-like middle and hind- 

 legs, but with spinous, raptorial fore-legs, belong to the family Emesid^. In the 

 latter the eyes are placed generally about midway between the front and base of the 

 head, and in a few genera, such as Licteva, Orthunga, and Stenolemus, are extrava- 

 gantly large and predominant for such a small cranium. Several subfamilies have 

 been founded within the limits of this group, upon characters of apparently minor 

 value when taken in connection with the sum total of their structure. The first of 

 these, called Emesida by Dr. Stal, is composed of species having only a single nail 

 upon the fore-tarsus. It is represented best in the United States by a very long spe- 

 cies, JEmesa longipes. Its ground color is cinnamon-brown or fulvous, with the upper 

 surface of the abdomen more or less reddish, pale stripes on each side of the head, a line 

 also on the middle of the pronotum, and the margins of the hind-lobe also pale. The 

 fore-thighs are indistinctly and partly banded with pale testaceous, the middle and hind- 

 femora are twice banded near the tip with ivory white, and the shanks of the same 



