( Ixiv ) 



fiised with them, the sternum being, liowever, always preserved as a narrow 

 separate stripe. 



The coxa is inserted iu a groove formed by the sternal part of the 

 stornitc : it bears the trochanter (froc/i), and is supported behind by the merum. 

 It will lie observed from the fignres that the midcoxa is mnch slenderer than 

 the mernm, while the hindcoxa is larger than the respective merum. There 

 is a very remarkable sjiccialisatiou fonnd in the merum. The hinder edge of 

 the nienim is normally rounded ; but in Parhylia, Nephele, and other genera 

 the edge liecomes carinate and aiignlate ; in the higher Sesiiiiar and Philam- 

 pditine the angle assumes more and more the shajie of a sharp triangular 

 process, reaching the highest point of specialisation in Cephonodes (PI. LXIII. 

 f. 2). The mesosternal merum shows this specialisation first, the metasterual 

 one slowly following. The processes project so far sideways that there is room 

 for the femur between the process and the breast. The femur is generally fonnd 

 in this position. The object of this specialisation is doubtless to prevent the 

 legs and the incision between meso- and metathorax from being a hindrance 

 in the darting flight of the insects. This becomes quite evident when we 

 compare the abdomen, wliich is closely appressed to the breast in the forms 

 with strongly angnlated merum, and bears very strong and flat spines, making 

 the abdomen very smooth. 



In the upper corner between coxa and mernm we find the trochantinus 

 {tchin), a small ])late wliich is more or less subglobose. The femora do not 

 offer any characteristic points. It is a curious fact, however, that they remain 

 always simple, even in cases where the tibia has become strongly spinose. 

 Tibia and tarsus undergo several modifications. Their relative length is often 

 variable either specifically or generically. A tibia clothed with scales and some 

 hairs, and truncate at the end, may be called a normal one. The apex of the 

 foretibia is often produced into a strong process (a thorn), which character is 

 sometimes of generic, sometimes only of specific value (PL LXIV. f. 16). Such 

 a thoru is found here and there in all subfamilies (except Choerocampinae). It 

 is a specialisation often combined witli other specialisations. It would, however, 

 be erroneous to say that a species possessing the thorn was in every respect 

 more specialised than the allied species which is devoid of that character. 

 For instance, Ceplionotles pints has an armed foretibia, while ki/las possesses 

 no thorn, but /////nx has a decidedly more specialised sexual armature. 



The spinosity of the tibiae is often an accessory character found in the 

 species which show reduction in the appendices of the head and thorax. But 

 the appearance of the spines is not invariably associated with a reduction of 

 the legs in length, nor are the spines always met with on reduced tibiae. 

 Spinosity of the tibiae occurs commonly among AcheroHtiiiiae and AmbiiUcmae ; 

 it is also found in some genera of Sphincjidae semanopliorue. The spines appear 

 first near the apex of the tibia, and the foretibia is the first, the midtibia 

 the second, and the hindtibia the last to acijuire sj)inosity. The liindtibia is 

 frequently mnch more densely spinose than the midtibia, and the foretibia 



