LEPIDOPTEROUS INSECTS. 35 



Genus PHAL^ENA, Latreille. 



The antennae are setaceous, short, simple, pecti- 

 nated or plumose in both sexes, or in the males 

 only ; tongue often small ; lower palpi almost 

 concealing the upper, nearly cylindrical or conical, 

 short, and covered with small scales ; wings large, 

 extended horizontally, or slightly sloped, and 

 the posterior border in many species angular or 

 dentated. 



This genus comprehends nearly that division of the Linnaean 

 genus Phalcena termed Geometra. Almost all the caterpillars 

 are smooth, with a slender elongated body, and on the backs of 

 many are eminences or warts resembling the knots or buds of a 

 small branch. They live solitarily, and feed on vegetables. 

 Some eat only the leaves of certain trees, while othei-s feed in- 

 discriminately on many. They walk by approximating the feet of 

 both extremities, and raising the intermediate portion of their 

 body into a ring or arch. Their progression is accomplished by 

 measured projections of their anterior feet, the posterior ones 

 being brought close up to the others at every step, the body 

 rising at same time into an arch. This mode of walking has 

 given rise to the application of the term Geometrce, or measurers 

 of land, by which the genus has been characterised. These ca- 

 terpillars are farther remarkable for the manner in which many 

 of them attach themselves to the branches of trees, and which 

 proves them to be possessed of muscular strength in a great de- 

 gree. Some fix their posterior feet on a small branch with the 

 body placed vertically, and remain immovable in this position 

 for hours, and others appear in attitudes which require the 

 exertion of still greater muscular power. When the leaf is 

 touched upon which one of these caterpillars is placed, it drops 

 off, but does not fall to the ground, having always a silken thread 



