38 ACADEMY OF NATURAL SCIENCES 



such velocity as to be projected several inches. No inflamma- 

 tion or discharge follows, but the sac immediately closes and heals. 

 Sometimes the worm is so small as to resist this mode of ex- 

 traction ; a piece of tobacco leaf is then gummed over the tumor, 

 (usually with an exudation from the skin of a plantain •,) the 

 worm dies in a few hours, and is then readily removed by 

 squeezing the part. I have nothing to add to the description of 

 the larva in the text, as emended by me, except to say that my 

 specimens were regularly clavate, not at all depressed ; the form 

 mentioned above was perhaps owing to contraction, produced by 

 the liquor in which the specimen was preserved. The figures 

 given by Mr. Goudot are regularly oval, and not at all clavate. 

 The name Gusano del Monte is commonly applied to the worms 

 by the natives, while the insect is called Zancudo gusano; the 

 word Zancudo means simply long legged, and it is difiicult to 

 understand how it could be applied to a species of Cuterehra. 

 The natives assured me that the fly was frequently seen, that 

 it was of a grey color, and resembled an ordinary mosquito, ex- 

 cept in being larger. I imagine that some species of Tipula 

 was. meant. A similar superstition in the United States has con- 

 ferred upon those harmless insects the fearful title of Gallinip- 

 2)ers. — Leg.] 



[From Vol. 3, 1823.] 

 Descriptions of Dipterous Insects of the United States. 



Kead Dec. 24th, 1822. 



The dipterous insects, from which the following descriptions 

 are drawn out, were chiefly collected by myself, during the late 

 expedition to theKocky Mountains under the command of Major 

 Long, and patronage of Mr. Calhoun, the present Secretary of 

 War. 



Of these insects, many appear to be common inhabitants of 

 the United States, throughout the immense region included by 

 the Rocky Mountains and the Atlantic ocean, between the parallels 

 of latitude 35° and 41° north; others are probably restricted to 

 the Western States, and some were seen only in the vicinity of 

 the Missouri river ; along the base of the great northern Andes, 

 where numbers of new and highly interesting animals and plants 



[Vol. III. 



