48 Journal New York Entomological Society. [Vol. xv . 



entirely different condition from that prevailing in Pasimachus. It 

 is very widely distributed and represented in temperate North 

 America by about twenty-five species, some twenty of which I have 

 had the opportunity to examine. 



Of the entire number, seven (C. haydeni Horn, C. subceneum 

 Chd., C. moniliatum Lee, C. discors Lee, C. wilkesi Lee, C. luxa- 

 tum Say, and C. latipenne Horn) are practically apterous, their wing 

 vestiges being hardly visible without the aid of a lens. The distribu- 

 tion of these ranges northwestward from Kansas, and the wingless 

 forms reach their maximum development in the northern Pacific 

 states. Nearly all (except C. haydeni, which I have not seen) form a 

 well marked group definable on characters aside from winglessness, 

 and in all, the elytra show the characteristic anchylosis which abso- 

 lutely prevents the raising of the elytra above the body and thus pre- 

 cludes even an attempt at flight. In C. palmeri Horn, the wings 

 are also short, and reach only about two thirds the length of the 

 elytra, being only eight millimeters in length. This species, too, has 

 the elytra anchylosed although it does not fall into the group contain- 

 ing the wingless species. 



Aside from the subapterous forms, an interesting condition is to 

 be seen among some members of the genus which are capable of 

 flight. Two of our most common species in the eastern United 

 States, C. scrutator Fabr. and C. calidum Fabr., show in the wings 

 differences which are evidently adapted to their different habits. 

 The former is diurnal, and to a great extent arboreal, ascending trees 

 to obtain the caterpillars of which its food consists. 



The latter species is terrestrial and nocturnal or crepuscular in feed- 

 ing habits. This fact is sufficiently evidenced by the frequency with 

 which it is found among the insects eaten by the common toad, while 

 its ability to fly well on occasion is shown by the number attracted to 

 electric street lights in cities on summer evenings. It shows a distinct 

 correlation in its wings which are smaller and more delicate than 

 those of scrutator. 



In the case of Calosotna scrutator and its European congener C. 

 sycophanta, the maintenance of strong wings is a necessity or at least 

 a great advantage and comes well within the province of action of 

 natural selection. 



On the contrary, the origin of wing vestiges, like those of the 

 various apterous species previously referred to, from a condition of 



