212 The Ohio Journal of Science [Vol. XX, No. 6, 



Technical Description. — Length S mm. ; maximum width 3.5 mm. 



Body robust; ground color yellowish-white marked with black. On 

 upper margin of head a black transverse band extending from eye to 

 eye; a like band connecting the lower borders of the eyes; thorax of 

 the ground color, a black band extending near the anterior margin from 

 base of wing pad to wing pad ; a dorsal median line of the ground color 

 extending from head, through pronotal horn, to -tip of abdomen; this 

 median line bordered with fuscous on thorax; each abdominal segment 

 on dorsum heavily banded with black, broken on each side, with excep- 

 tion of the last three segm.ents, by a heavy band of red, variable in 

 width; anterior pronotal process porrect; pronotum not entirely cov- 

 ering mesonotum dorsally but extending posteriorly as far as the meta- 

 notum as an acute point; wing pads fully developed, second pads not 

 extending quite as far posteriorly as the first; legs flavus. 



Head much deflexed; frontal tuberosites small; eyes bright red; 

 ocelli pale; clypeus distinct; beak well developed, light fuscous. Pro- 

 thorax well developed and strongly chitinized; anterior process project- 

 ing far forward as a compressed blunt cone, black; mesathorax and 

 metathorax distinct ; two simple, heavy, black, divergent spines arising ' 

 one on each side of the mesonotum ; wings pads long. Abdomen greatly 

 swollen, no dorsal spines; under surface yellowish- white marked with 

 fuscous along margins, in female showing impression of ovipositor, 

 fuscous. Legs flavus without markings, hirsute. 



Note: On September 16, 1919, nymphs and a hornless adult of P. vittata 

 were sent to the Ohio Agr. Expt. Station from Yellow Springs, Ohio, where they 

 were feeding on the cut-leaved birch (Betula alba var.) Some of these nymphs, 

 which appeared to be in the last instar, were hornless, others homed. This 

 raises the interesting question as to whether hornless adults are produced from 

 hornless nymphs and homed adults from horned nymphs. 



Ohio State University, Columbus, Ohio. 



EXPLANATION OF PLATE I. 



Fig. 1. Adults and last instar nymphs on oak branch, showing their gregarious 



habits. Nat. size. 

 Fig. 2. Beginning above: (a) Adult of the color variety, Platycotis quadrivittata, 



horned form, (b) Last instar nymph, (c) P. vittata, unhomed form. 



(Greatly enlarged.) 



