634 EEPORT UNITED STATES GEOLOGICAL SURVEY. 



cess of extrication is as follows : While it lies nearly motionless it puffs 

 out the thin, loose skin connecting the back of the head with the front 

 edge of the prothorax. The distension of this part probably ruptures 

 the skin, which slips over the head, the body meanwhile curved over 

 until the skin is drawn back from the head ; when the latter is thrown 

 back it withdraws its antennte and legs, and the skin is in a second 

 pushed back to near the end of the abdomeu ; finally it draws its hind 

 tarsi out of the skiu, and in a moment or two more the young locust 

 frees itself and walks actively off, sometimes, however, with the cast 

 skin adhering to the end of the abdomen. 



Before the molting of the amnion the body and legs are soft and flabby; 

 immediately after, it walks firmly on its legs. At 11 a. m. most all, one 

 or more hundred, had hatched. They are pale-reddish, however, as in 

 the embryo ; by 3 p. m. they had begun to turn dark, and by 9 of the 

 next day all were dark colored, as in the following description : 



Description of the layra. (Plate LXII, Fig. 3). — The following description is taken from 

 living young as they had just hatched iu Salem, Mass., January 22, 1877 from eggs re- 

 ceived from Mr. A. Whitman, of Saint Paul, Minn. The larva has a larger head, 

 and smaller abdomen than the pupa and has no rudiments of wiugs. They were 

 blackish, marbled with flesh-color, with a dorsal white line behind the head. Legs 

 flesh-colored, spotted irregularly with black. Hind thighs (femora) spotted with 

 black, much as in the adult ; toe-joints (tarsi) black. Head very large iu proportion 

 to the rest of the body ; abdomen small, tapering rapidly toward the tip. Length, 

 0.17 inch. In another specimen (three living ones only examined) the back of the 

 body had a reddish tint, as in older specimens observed living in Colorado. 



Pupa (Plate LXII, Figs. 3, 4). — Ground-color, a deep reddish salmon-color on the head, 

 body, and legs. Front of head below the autannse black, marbled with white lines. 

 Prothorax with a curved, broad, black longitudinal band on each side of the median 

 line, and below a squarish black spot separated from the black band above by a con- 

 spicuous white stripe, and with two white spots on the lower edge. Rudimentary 

 wings black, with fine pale lines and reddish flesh-colored along the costal edge. Hind 

 legs blackish on the outside of the thighs (femora), interrupted by fine, salmon-colored 

 lines. Abdomen whitish above and on the sides, sported and marbled with black, 

 forming broken lines ; ventral side flesh-colored, not spotted. Hind shanks (tibite) 

 black beneath, above flesh-colored, with the spines black. Length, 0.65 inch. De- 

 scribed from several living specimens taken at Manitou, Colo., July 16 ; hundreds of 

 others seen iu diflerent parts of Colorado not apparently differing on casnal examina- 

 tion. 



In addition I may quote Mr. Riley's description based on living speci- 

 mens observed in Missouri : 



The pupa is characterized by its paler, more yellow color, bringing more strongly 

 into relief the black on the upper part of the thorax and behind the eyes; by the 

 spotted nature of the face, especially along the ridges ; by the isolation of the black 

 subdorsal mark on the two anterior lobes of prothorax, and by the large size of the 

 wing-pads, which, visible from the first molt, and increasing with each subsequent 

 molt, are now dark, with a distinct pale discal spot, and pale veins and borders. The 

 hind shanks incline to bluLsh rather than red, as in the mature insect. 



Adult (Plate LXII, Figs. 1, 4, e,5, 6). — After repeated examination of the variations of 

 this si)ecies as compared with those of C. femur-rubrnm, the only reliable characters I 

 have been able to fiud are the following : The male and female C. spretus (normal Rocky 

 Mountain form) diliers from C. femur-nth rum in its much larger size, its proportion- 

 ately longer and larger wings and usually lighter tints, aud the larger, more dis- 

 tinct spots on the wings. I can see uo difl^erence in the ovipositor of the female. 

 The most constant difference is iu the form of the end of the male abdomen, which 

 is narrow, elevated, aud more or less deeply notched (see Plate I, Fig. 6), while in 

 the male of C femur-rubrum it is well-rounded, full, swollen, and the edge entire, 

 with very rarely a slight tendency to a notch. The largest male from Colorado in my 

 collection measured 1.30 iuches. The small variety Atlanis I regard as a A'ariety of 

 this species, and not femu7'-ruhrum, because it has the well-defiued notch in the narrow, 

 high abdominal tip. My Iowa specimens are darker than those from Colorado, Mis- 

 souri, and Kansas, but a tine male from Arapahoe Peak, Colorado, is full as dark as 

 those from Iowa. 



