278 REPORT UNITED STATES ENT'OMOLOGICAL COMMISSION. 



thus reDdered easier. The chorion is the egg-shell, and is a dense, rather 

 thick, horny membrane. It is covered by a hard crust secreted by the 

 sebific gland. This crust is pitted hexagonally. The ripe embryo is pro 

 tected within the egg by two membranes. The outer is the serous mem- 

 hrane, and is of the form of and lies next to the chorion, while the inner is 

 the amnian, and envelops the body and each separate limb. While this 

 membrane in most insects is structureless, we have found that in the 

 locust it is composed of convex cells, the membrane seen in outline 

 being rough, like the cornea of an insect's eye. Although we have 

 not seen the larva actually burst its way out of the egg in more than 

 two instances, yet on the examination of between fifteen and twenty 

 deserted egg-shells, we have, without an exception, noticed in them 

 one, more usually two, slits extending from the head end to the middle 

 of the egg. The egg-shell is without doubt burst open by the pufiing- 

 out or expansion of the membrane connecting the head and protho- 

 rax, just as the common house-fly, or flesh-fly, bursts off the end of its 

 pupa-case by the puffing-out of the front of the head. In one case, we 

 saw a large piece of the egg-shell (chorion) fly off from in front of the face 

 while the face of the embryo puffed slightly out, and in another instance 

 the whole anterior end of the shell came off. In the locust, we have 

 observed, as will be seen farther on, that the amnion is ruptured by the 

 forcible expansion of the membrane behind the head, the larvae before 

 walking lying on their backs or sides and forcing this membrane out- 

 ward. This action probably begins before the shell is burst, and seems 

 amply sufficient to burst the chorion and serous membrane. The outer 

 crust deposited from the sebific gland is fragile and easily broken and 

 peeled off by rubbing the egg between the fingers, leaving the chorion 

 beneath. The pressure thus exerted must be a lateral one, and suffi- 

 cient to rupture the dense chorion. 

 On removing the living embryo from the egg-shell (Fig. 18), it is found 

 that it lies with the legs folded on the side of the 

 body, the fore and middle pairs folded directly 

 across the thorax, while the hind pair are laid 

 along each side of the abdomen. The antennae lie 

 on the face, each side of the clypeus and labrum, 

 or upper lip. The eyes are dark reddish, and the 

 head, limbs, and cross-lines on the back of the 

 body are reddish mixed with yellow. Beneath, the 

 body and legs are white. By putting the eggs in 

 alcohol, the shell becomes more transparent, so 

 Fig. is.-Embryo locnst ^^^^ ^^^ head, cycs, limbs, and reddish portions of 

 Emerton P"'*'''" ^^^^""'^ the body become visible. Length of embryo at 

 time of hatching, 0.21 inch. Described from living 

 specimens received from Mr. S. D. Payne, Kasota, Le Sueur County, 

 Minnesota, March 1, 1877. Either during the night of the 13th or early 

 in the morning of the 14th of March, nearly all the larvae (the eggs hav- 



