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C Hncinnati Society of Natural History. 



should be found in numbers about a clump of grass or grain plants is 

 not surprising, as a large number of eggs deposited in such places 

 would account for their numbers, but after crossing a roadway or 

 plowed field, and reaching evenly distributed plants on the opposite 

 side, they do not spread themselves out over any considerable territory, 

 but even when their numbers are limited, they will congregate on a 

 few plants, precisely as if they had, somewhere, been obliged to fol- 

 low this habit, during a long period of time, as a necessary precaution 

 against extermination. That this characteristic habit should be fol- 

 lowed throughout a period of fifty or even one hundred years, in a 

 locality where such was not only unnecessary, but even detrimental, 

 is not at all improbable, so long as it does not threaten the extermina- 

 tion of the species. 



Mr. W. H. Hudson in his "Naturalist in La Plata," p. 241, 

 informs us that, on the pampas of South America, some of the wood- 

 peckers seek their food 00 the ground and also nest in the banks of 

 streams, yet even where their living in the midst of treeless plains has 

 resulted in structural modification in accordance with their altered 

 way of life, they still retain the primitive habit of clinging, vertically 

 to the trunks of trees, although the habit has lost its use. And, again 

 the same author, on page 18 of the same work, tells us of a species of 

 opossum, Didelphys auritus, also on the same pampas, and while 

 every way fitted for an arboreal life, yet is everywhere found on the 

 ground where it has probably been a dweller for thousands of years, 

 but if one is brought to a tree it will take to it as readily as a monkey. 

 Why, then should not Blissus leucopterus retain its maritime instincts 

 on the American pampas of the Mississippi valley ? There is another 

 characteristic habit of this species that we may, perhaps, trace back to 

 some ancient time when it was essential to the perpetuity of the race. 

 Although Dr. Packard has found it on the summit of Mount Washing- 

 ton, New Hampshire, at an elevation of 6,300 feet, and Prof. Gillette 

 writes me of its occurrence, rarely, near Fort Collins, Colorado, at an 

 altitude of 5,500 to 6,000 feet, inside the foot hills, Prof. Cockerell, 

 who collected carefully in Colorado for several years, about West Cliff, 

 Custer County, at an approximate elevation of 7,000 to 8,000 feet, did 

 not find it at all. It is reported from Volcan de Chiriqui, Panama, at an 

 elevation of 6,000 feet. (Biologia Centrali-Americana, vol. I, p. 196.) 

 How common Dr. Packard found it on Mt. Washington, I do not 

 know, but as Mrs. Slosson has collected very carefully on the moun- 



