UEMIl'TEKA— HOMOPTEEA— CEKCOriD^. 32 1 



tegmina united to each other by a cross- vein, to which they bend ; they too 

 are lost before the tip. The wings are not sufficiently preserved to charac- 

 terize, but appear to agree in general character with those of Triecphora. 

 Abdomen more than twice as long as the rest of the body, topering regularly 

 to a pointed extremity. 



Table of the sjjecies of Petrol ijslra. 



Pale bands of tegmina occupying hardly more space than tbe dark grouud 1. /'. ijiiiauliM. 



Pale bauds almo.st supplanting tbe normal dark ground of tegmina d. P. hcrox. 



1. Petrolystra gigantea. 

 PI. 20, Figs. 5-7. 



Peirohjstra gigavtea Sendd. Bull. U. S. Geol. Geogr. Snrv. Terr., IV, 531-532 (1878) : in Zittel, Haudb. 



d. Pala?ont., I, ii, 781, Fig. 902 (1885). 



Two nearly perfect specimens, reverses of each other, were picked up 

 by a child just as I reached the quarries at Florissant, on my first visit to 

 them, and another, a fragment of a wing, was afterward found in the same 

 place. The head was apparently dark-colored, the thorax not so dark, 

 delicately and softly shagreened, with a slight median carina The tegmina 

 ai'e almost similarly rugulose ; the costa of the same is pretty strongly con- 

 vex at base, very slightl}'^ convex beyond the middle of the basal half; the 

 posterior border is slightly excised at the tif) of the clavus, and the outer 

 margin is oblique, being angularly excised at the posterior angle, although 

 rounded throughout. It is dark, darkest at base and gradually grows 

 lighter, more fuliginous toward the tip (although all the specimens do not 

 show this), and is traversed by four equidistant transverse pale bands, the 

 basal one reduced to a spot in the middle of the extreme base, where it oc- 

 cupies about one-third the width of the wing; and the apical one rather 

 cloudy, half as broad as the breadth of the tip and as far from the tip as 

 from either border, equal, two or three times as broad as long, sinuoue or 

 lunate ; the other two are more distinct, with sharply defined borders and 

 irregularly sinuous ; the outer of the two traverses the entire wing, touch- 

 ing the costal border, however, by only the tip of the rounded extremity, 

 while it expands upon the posterior border ; the inner of the two is rounded 

 at either extremity, fails of reaching either border, and is constricted just 

 beneath the radial vein ; both of these bands average in width the breadth 

 of the interspaces. 



VOL XIII 21 



