296 W. D. FUNKHOUSER 



The rank of the Membracidae among the other Homoptera is, as has 

 been stated, a mooted point. The exceptional and bizarre development 

 of certain thoracic regions seemingly represents an extreme degree of 

 specialization; the poorly developed nervous system, on the other hand, 

 suggests a low position in the scale of the Hemiptera. It is believed 

 that a comparison of the sclerites of the family with those of other homop- 

 terous forms may throw some light on the question of general homologies 

 and serve to aid in the correct interpretation of structural development. 



To make this report of the greatest value, the forms studied have not 

 been limited to the species of the basin, but material has been drawn from 

 all parts of the world. About two hundred species, representing about 

 forty genera, have been examined, and for many of the species nymphal 

 and imaginal material has been compared. 



TECHNIQUE 



In most cases the insects were boiled in caustic potash, dehydrated and 

 cleared, and studied unmounted under the binocular. It was often found 

 necessary to cut the body wall down the median dorsal line and mount the 

 exoskeleton, opened out flat, in balsam under a large cover slip. The 

 head was usually mounted separately, since the angle at which the head 

 joins the thorax in the Membracidae makes a mount of the complete 

 skeleton unsatisfactory. Small forms, spread under pressure, made 

 excellent slides for study under the compound microscope. The method 

 suggested by Crawford (1914:4), of sectioning away half of an embedded 

 specimen with the microtome and dissolving the paraffin from the unsec- 

 tioned half, gave good results but was not found necessary for most forms. 

 Without exception the last nymphal instar, when obtainable, showed best 

 the delineations of the sclerites. This was probably due to the fact 

 that at this stage of development the exoskeleton is not entirely chitinized 

 and the regions between the sclerites are therefore exaggerated. 



For comparative stud}' the gross dissections were checked bj' the use 

 of microtome serial sections, both cross and longitudinal. In this method 

 the insects (fresh material) were carried thru the following series: Brasil's 

 fluid (cold), 12 hours; 70-per-cent alcohol (wash), 24 hours; stain in toto 

 borax carmine, 72 hours; destain 70-per-cent acidulated alcohol, 24 hours; 

 85-per-('ent alcohol, 24 hours; 95-per-cent alcohol, 24 hours; absolute 

 alcohol and cedar oil, 24 hours; cedar oil, 48 hours; section from 6 to lOju; 



