OF WASHINGTON, VOLUME XVI, 1914 57 



in front of the inferior. At the end of each cunea there is a thick- 

 ening of the membrane which on the inside forms a small notch 

 to which muscles are attached. I call these thickenings relatively, 

 the anterior (an) and the posterior (pn) cuneal notch. Another 

 similar notch is found in the upper portion of the anterior cunea; 

 I call this the superior cuneal notch (sri). Finally there is a fourth 

 notch on the median ventral line of the posterior cunea; this I 

 term the ventral cuneal notch (vn). 



THE LATERAL ZONE 



Between the posterior cuneal notch of one intersegmental skin 

 and the anterior cuneal notch of the succeeding inter segment a 1 

 skin is found, on the inside of the integument, a staff -like or even 

 caririated apodeme, which on the outside appears as a deep groove. 

 This groove has been named by Doctor Hopkins the pleural suture 

 (pi). Above and parallel with the pleural suture is found a 

 similar one which I call the antipleural suture (anti). This is some- 

 times more, sometimes less developed than the pleural suture. 

 It is somewhat shorter than the pleural suture and does not reach 

 either of the margins of the segment. The bandlike region be- 

 tween these two sutures I call the lateral zone. This lateral zone 

 has, as already pointed out by Dr. David Sharp in his hand- 

 book, 1901, p. 90, a mechanical use in the dorso-ventral compres- 

 sion of the larval body corresponding to that of the intersegmental 

 skin in the telescoping compression, and it is stiffened on the in- 

 side by a circular thickening which touches both the antipleural 

 and the pleural suture. This circular thickening limits an area, 

 which on the outside is elevated and rounded; it is the area which 

 has been termed the pleural lobe (pll) by Doctor Hopkins. The 

 rest of the lateral zone is divided by oblique sutures into four 

 small triangular parts, two before, and two behind the pleural 

 lobe. I call these respectively the protopleurite (prpl), the deu- 

 teropleurite (dpi), the tritopleurite (tripl) and the tetrapleurite 

 (tetpl). All of these four small areas are prolonged more or less 

 upward along the superior cunea. 



The whole lateral zone can be compressed by two systems of 

 perpendicular muscles. The muscles of the first system run 

 upwards from the middle of the pleural suture ; while the muscles 

 of the other system run downward from each end of the antipleural 

 suture. When the muscles are relaxed, the pleural and antipleural 

 sutures are again separated by the elasticity of the pleural lobe 

 and of the oblique sutures. 



