FAMILY ZYG^JNIDJE. 35 



large and pentangular, the longest side being the posterior 

 edge which is a little convex, and scarcely angulated in the 

 middle. Wings broad ; the primaries a little less than half 

 as long as broad. Costa full, convex towards the apex, which 

 is rounded acute. Outer margin half as long as the costa, 

 more than usually oblique. Inner edge two thirds as long as 

 the costa. The costal area is very narrow in this genus, since 

 the subcostal runs very near the edge of the wing, and its 

 first, second and third nervules are very long and parallel to 

 the costal edge. Third subcostal simple, the fourth arises 

 midway between the apex of the wing and the origin of the 

 second subcostal. Fifth slightly removed towards the middle 

 of the discal area, arising directly opposite the first and- 

 second median nervules, the origins of which are united, the 

 second being straight, while the first and third are arched, the 

 last named one arising very near the two first. They then 

 enclose a very regular semioval area. Fourth median arises 

 at a distance from the third equal to the length of the two discal 

 nervules, which are straight, and unitedly are directed exactly 

 at right angles to the costa. 



The secondaries are broadly triangular, reaching nearly to 

 the tips. The costa is decidedly convex within its middle, the 

 apex is produced, but very much rounded, as in the internal 

 angle, though the inner edge is itself very straight, and is one 

 half as long as the costa. The lower discal nervule is directed 

 obliquely outward, and both are curvilinear. The space between 

 the first and thiid median is acutely triangular, since the ner- 

 vules are nearly straight. 



The legs are long and slender, the hind tibiae with two pairs 

 of small acute unequal spurs, of which the inner pair are the 

 smaller. Hind tarsi longer than the hind tibias, and the first 

 tarsal joint is a little shorter than the three succeeding ones 

 taken together. Abdomen twice the length of the thorax, pro- 

 vided with minute lateral tufts, slowly tapering towards the tip 

 which is subacute, though not abruptly pointed. 



The colors of the genus are deep indigo blue, with a smoky 

 tinge on the primaries, a lighter blue abdomen and saffron 

 "collar." The nervules may be concolorous or as in the very 

 interesting C. cressonana from Pike's Peak, described by Mr. 

 Grote to whose kindness I am indebted for a specimen of this 

 rare species the median and submedian nervules are white 

 and thus remarkably distinct. The size of the genus is large, 

 both species expanding two inches and a half. 



