Characters of the Species. 



21 



larvae there is a distinct pale line along the medio-dorsum ; in 

 others there is no trace of it. 



In the following table of measurements, introduced for com- 

 parison with that given of femur-rubrum, the same rules were 

 adopted as in the other case, and particular pains were taken to get 

 specimens from as many parts of the ravaged country as possible ; 

 also, by study of the structural and other peculiarities of spretvs 

 to guard against the chance mixing of specimens of femur-rubrum. 



CALOPTENTJS SPRETTJS. 



Measurements of the Male in Hundredths of an Inch. 





Whole length 

 from front of 

 head to tip of 

 wing. 



Length of wing 

 beyond base 

 of tibia. 



Length of 

 abdomen 

 beyond base of 

 tibia. 



Length of wing 

 beyond tip of 

 abdomen. 



Lowest 



1.10 



0.25 



0.02 



0.20 



Highest .... 



1.40 



0.43 



0.12 



0.39 



Average 



1.28 



0.34 



0.05 



0.31 





Measurements of Female. 





Lowest 



1.15 



0.28 



0.04 



0.13 



Highest 



1.53 



0.52 



0.19 



0.39 



Average 



1.35 



0.35 



0.10 



0.27 



Finally, besides the structural and more reliable characters 

 already given, the two species may, in general terms, be distin- 

 guished by the following less reliable and more inconstant charac- 

 ters as presented in cabinet specimens : Spretus is the larger 

 species ; the antennas are slightly shorter and paler ; the occiput 

 and two anterior lobes of the prothorax are more livid and darker ; 

 the third lobe of prothorax broader ; the dark, subdorsal, pro- 

 thoracic mark running from the eyes less pronounced ; the oblique, 

 yellow line from base of wines to base of hind thighs more often 

 obsolete ; the front wings paler toward tips, more ferruginous at 

 base, with larger, more conspicuous spots ; the anal abdominal 

 joint of male also much paler ; the cerci and valves in the female 

 generally shorter and more robust. 



In femur-rubrum the general hue is more olivaceous and darker, 

 the black mark behind eyes is broader, and that on prothorax 

 also broader, more straight beneath, and seldom enclosing white 

 marks ; the pale stripe from base of wing to hind thighs is more 

 conspicuous and the spots on wings subobsolete. 



Such aie the distinguishing features between these two insects, 



