110 ZYGiENIDiE AND BOMBYCID.E 



Genus LITHOSIA. Fabricius. 



Head free, broad, finely scaled, smooth ; front nearly square ; vertex 

 broad. Eyes prominent. Palpi short, porrect. 



Thorax globose, smooth. Abdomen slender, not reaching the end 

 of hind wings. Legs slender, smooth ; hind pair with two pair of 

 spurs. 



Anterior wings very long and narrow ; three times as long as broad. 

 Costa nearly straight ; apex rounded ; outer margin slightly oblique ; 

 inner margin straight, nearly parallel with costa. Costal vein long- 

 Subcostal five-branched, ist thrown off near the base uniting with the 

 costal ; remaining branches thrown off in the following order, 5th, 

 2d, 3d, the latter being furcate ; 4th springs at the origin of 3d, and 

 with 5th goes to the outer margin. Median vein three-branched ; ist 

 and 2d united at the base ; 3d very long, distant from 2d, springing 

 near the base of the wing. 



Posterior wings long, nearly twice as broad as the primaries ; outer 

 margin oblique, rounded ; costa straight. The wings folded round 

 the body when at rest. 



The three American species may be tabulated thus : 



Wings slate colored, ------ Z. argillacea. 



Wings white. 



Head white, ------ Z. Casta. 



Head yellow, ------ C Cephalica. 



l.-LITHOSIA AEGILLACEA. (Pl. 7, fig. 13.) 



Lithosia argillacea, Packard, Proc. Ent. Soc. Phil., vol. 3, p. 98. 



(1864.) 

 Lithosia bicolor, Grote, Proc. Ent. Soc. Phil, vol. 3, p. 74. (1864.) 



5. — ?. " Slate color and yellow. Lustrous slate color. Palpi 

 yellow, with a few slate colored scales near the tips. Prothorax yellow, 

 continued on to the costa of the primaries on the upper and under 

 side of the wing, nearly to the apex. Costa of secondaries also tinged 



