Biology of the Membra cidae of the Cayuga Lake Basin 331 



normal in such general points as the number, position, and relative size 

 of the segments, and the attachment to the torso. The individual seg- 

 ments, however, are much inclined to variation thruout the family. 

 The simplest type of leg is found in the subfamily Smiliinae, in which 

 there are but few differences in leg structure in the various genera (Plate 

 XXXV, 1-5). The legs increase in length from before backward in practi- 

 cally all the genera, but in a few the first and second pairs are about 

 equal in length. The hind legs are always the longest. It is possible that 

 the relative leg lengths may be of value in systematic diagnosis, but the 

 character would be a very hard one to determine in ordinary mounted 

 material because of the fact that the legs are so often tightly folded against 

 the lower part of the body. In life the front legs usually point forward and 

 the second and third pairs backward. The front legs, in fact, are attached 

 so closely to the head as to completely hide the mouth parts and the 

 gular regions when the insect is at rest in its natural position. All the 

 legs, and particularly the posterior pair, are very well developed, as would 

 be expected from the jumpmg habits of the insects. The basal parts are 

 heavy and swollen and cover most of the ventral surface of the thorax. 

 The legs are much inclined to pubescence and often bear spines. 

 Particular development of such structures will be discussed under the 

 separate segments. 



The coxae are heavy and stout. The posterior pair are usually the largest 

 and closest together, and show the greatest tendency toward peculiar 

 development. Each coxa consists of a flattened plate which fills up the 

 coxal cavity, and a distal projection to which the trochanter is articulated. 

 This distal projection is often bent at an angle to the other two-thirds 

 of the segment and projects ventrad. Between the body of the coxa 

 and its distal end is found in some cases a constriction, or neck (Plate 

 XXXV, 6-9). The articulatory surface is generally swollen and often 

 apparently distorted. In a large number of species the lateral end of the 

 middle and the hind coxae is distinctly cut off, leaving a triangular piece 

 laterad of the body of the segment but in the coxal cavity. In the adult 

 this is represented by a deep suture (Plate xxxv, 1-2), and boiling in caustic 

 potash shows that this is really a division between the chitinized areas. 

 This separate piece is believed to be a subdivision of the coxa and originally 

 a part of that sclerite. A comparative examination of the cicada shows 

 the segment still more distinct and differently located in that insect 



