Characters of the Species. 



25 



artificially transported in the egg and hatched in the 

 Atlantic States.* 



It is in this, as it is in almost every other instance where 

 large material from widely different parts of the country 

 is examined ; the lines which are easily drawn between 

 species characterized from single individuals, break down, 

 and continually remind us of the arbitrary nature of spe- 

 cific definitions, and of the fact that most of the species, as 

 defined among lower animals and plants, have no real ex- 

 istence in nature. There are races of femur -rubrum which 

 approach even the larger differ entialis as much as they 

 approach spretus. In short, without speculating on the com- 

 mon origin, in the past, of all these species — and, indeed, 

 of all species composing present genera — we behold, in a 

 broad sense, a short-winged species (femur-rubrum) com- 

 mon to the whole country between the Rocky Mountains 

 and the Atlantic, giving way, in the higher altitudes alike 

 of the Rocky Mountain and the White Mountain, and 

 probably of the Alleghany regions, to a long-winged one ; 

 and the reason why the western long-winged species 

 is more disastrous than that of the East, is doubtless 

 due to its larger size and to the larger extent of table land 

 in which it breeds, as well as to the fact that the western 

 climate is more subject to excessive drouths, which cut off 

 the supply of nourishment at a time when the insects are 

 acquiring wings, and thus oblige them to migrate — such 

 conditions occurring much more rarely in the home of the 

 eastern species. In the lower country on either side of 

 the Mississippi, the typical characters of the three species 

 are more liable to vary and to approach one another. The 

 future orthopterist, as he studies material from all parts 



* See an observation by Mr. S. S. Rathvon, of Lancaster, Pa., whoconcludea 

 from experiment, that the climate there is " unwholesome " to the species. (Am. 

 Entomologist, II, p. 88.) 



