548 



HEMIPTERA. 



bears much the same relation to the C or i sice as the lice do to 

 the Membranacei (Cimex), or Podura and Lepisma to the 

 Keuropterous families above them. A comparison with the 

 Mallopliaga is still better, for in Thrips (Fig. 552) we find, 

 as in the last named group, free, biting mouth-parts, accom- 

 panied by a general degradation of the body. Though the spe- 

 cies are winged, yet the wings are partially aborted ; they are 

 long, narrow, linear, both pairs of equal size, as in the typical 

 Neuroptera, and by the frequent absence of any veins, either 

 longitudinal or transverse, and the long delicate silky fringe, 

 remind us strikingly of some minute degraded hymenopterous 

 Proctrotrypidce, Pteratomus (Plate 3, fig. 8), for example. 

 The mandibles are bristle-like ; the maxillae are flat, triangular, 

 bearing two to three-jointed palpi, and the labial palpi are 



present, but very short, 

 and composed of but two 

 or three joints. 



Chiefly on account of 

 these characters these in- 

 sects were placed in a dis- 

 tinct order, termed Thy- 

 sanoptera by Haliday, and 

 by many recent authors 

 they have been widely 

 separated from what seem to us their nearest allies. Latreille, 

 however, recognized their affinities to the Homoptera, while 

 stating that in their free biting mouth-parts they resembled 

 the Orthoptera, to which Geoffrey referred them. To us they 

 appear to be, as it were, degraded Lygaeids, and to preserve 

 the general form of that group, in the long head, the stout, 

 thickened fore limbs, and the large, square prothorax. They 

 have both compound and simple eyes, the latter three in 

 number. 



The antennae are long and slender, with from five to nine 

 joints. In some species the fore wings are comparatively 

 well developed, or, as Haliday states, they are "transformed 

 into broadish elytra, ciliated only behind, and with longitudinal 

 and transverse nerves. In some species the wings are want- 

 ing, at least in the males." (Westwood.) "The abdomen is 



Fig. 552. 



