Biology of the Membra cidae of the Cayuga Lake Basin 297 



benzine, 5 minutes; 95-per-cent alcohol, 5 minutes; 3-per-cent lyons 

 blue, 20 seconds; 95-per-cent alcohol, 3 minutes; carbol-xylol, 5 minutes; 

 mount in balsam. 



No attempt has been made in this study to work out the musculature, 

 altho it has been necessary to refer to certain developments of the skeleton 

 which function as points of muscle attachment. 



TERMINOLOGY 



The terminology used in the discussion of the sclerites of the head 

 follows that of Comstock and Kochi (1902), based on those of Kirby 

 (1802), Ilhger (1806), and Newport (1839). 



For the thorax the terminology follows that of Crampton (1909) and 

 that of Snodgrass (1909). Both of these follow largely the old work of 

 Auduin (1820). 



The terminology used in the discussion of the abdomen follows that of 

 Berlese (1909). 



GENERAL STRUCTURE 



The exoskeleton in the Membracidae is strongly but not uniformly 

 chitinized. The head and the thorax, particularly the latter, are hard to 

 the point of brittleness; but in the abdomen and in those parts of the 

 meso- and the metathorax that are covered by the pronotum, the impreg- 

 nation of chitin is much less heavy. 



The exposed parts of the cuticle — in the Membracidae much of th(^ 

 actual body surface is not exposed but is covered b}' the pronotal develop- 

 ments — are modified by remarkable and grotesque punctuations, ridges, 

 and areolations (Plate xxx, 1-8), the function of which is conjectural. 

 The commonest decoration consists of irregular arrangements of punctures, 

 varying in size and distribution but fairly constant in appearance. In 

 fact, this punctuation, whether deep or light, fine or coarse, dense or scant, 

 has been used by practically all systematic workers on the group, and there 

 can be no question as to the taxonomic value of such structures at least as 

 specific characters. These punctures are merely depressions, or pits, 

 extending into or even thru the cuticle but in no case perforating the 

 entire body wall. They apparently have no connection with tracheal or 

 glandular development and nmst be regarded as being merely superficial 

 sculpturing. Occasionally the pits give rise to hairs. This is, however. 



