244 CHARLES R. STOCKARD. 



On dissecting the egg the embryo is found to be curled around 

 in a rather constant manner, the head being usually, though not 

 always, near the opercular end. The long legs are folded back 

 and forth upon themselves in a very definite fashion as shown by 

 the camera drawing, Fig. 2. The antennae (A) pass down the 

 front of the head and then back along the ventro-lateral surface 

 of the abdomen being sometimes bent around the first pair of 

 legs. The point of most importance is that the femoral segments 

 of the legs are all directed obliquely away from the head. The 

 first pair of legs each of which is folded on itself four times does 

 not touch the sides of the head at all. The head and large eyes 

 are entirely uncovered and exposed. The femora of the first 

 pair of legs not only fail to mold their curves against the head 

 but the femora are so pressed against the thorax that the surfaces 

 which will subsequently be concave (in Fig. 2 between x and x] 

 are actually arched convexly. Thus it is seen that the mechanical 

 arrangement of the embryo's parts within the egg is not respon- 

 sible for the fit of the femur curve against the head. On the 

 contrary the curve seems to develop in spite of these arrangements. 



When hatching the embryo's head and body come forth from 

 the egg first, the antennas are then pulled out, the legs being the 

 last parts liberated from the shell, Fig. 3. It often happens that 

 the shell is carried around for some time dangling to the third 

 pair of legs. In Fig. 3 the well developed curves of the femora 

 are distinctly shown, x to x, and are being pulled in a direction 

 away from the head, yet as soon as the legs are free from the 

 shell the first pair may be straightened forward and their curved 

 femora fit neatly against the sides of the head. We see, there- 

 fore, that the curve of the femora to fit the sides of the head is a 

 character transmitted to all of the young and perfectly formed at 

 the time of hatching. It might seem that the origin of this 

 character was most probably due to the habit of the insects to 

 press the first pair of legs against the head. Gradually this 

 pressure developed a thin concave region of the femur of the first 

 leg which molded itself more and more perfectly to the contour 

 of the head. If this curve arose in any other way the second and 

 third pairs of legs might have developed at least a trace of such 

 a character though this is not absolutely necessary. It must be 



