10 



from the base it gradually narrows distally, forming a spatulate pro- 

 cess of varied length, which in most cases is truncate at the apex; in 

 a single case (smithi) it is bifid. 



The Valves or Clasps are very varied in structure ; the distal 

 area in all species is most strongly chitinized ; the simplest form is 

 shown in smithi in which the distal portion is bluntly rounded, a slight 

 tooth being formed about the middle of the outer margin, no armature 

 being present ; in the remaining species the distal end of the clasp is 

 divided into two distinct sections ; of these the dorsal one has been 

 termed by Scudder the "Lobe" (Proc. Bost. Soc. Nat. Hist., XIII, 

 284), the ventral one the "Blade." The Blade in the species under 

 consideration may be either drawn out into a long sharp upcurved 

 hook, more or less serrate on its upper margin, (hespcriaris and ncu- 

 mocgcni group), or be bluntly truncate (streckeri), or provided with 

 an apical ridge which juts forward to form a sharp tooth (yuccae) ; 

 in each case the upper margin is provided with a strongly serrate 

 chitinous rod-like structure which projects slightly forward into the 

 cavity formed by the two lateral clasps and the tegumen and uncus ; 

 this is doubtless analogous to the Harpe found in Noctuidae, Sphin- 

 gidae, etc., and has been termed by Scudder "Basal process;" in order 

 to avoid any misunderstanding we will refer to it as the Proharpe. 



The LoisE is well rounded apically, more or less covered with setae, 

 tho junction between it and the Blade occuring at the point of origin 

 of the Proharpe ; from this point a very slightly chitinized wedge-shaped 

 area extends backward into the valve, often for a considerable distance, 

 accentuating as it were the division between the dorsal and ventral 

 areas. 



The Penis may be curved apically or nearly straight ; it is usually 

 provided with some slight armature in the way of small spines or teeth. 



The female organs of copulation are most complex ; they may be 

 divided into the Vaginal Plate proper and the Postvaginal Plate. The 

 Vaginal plate consists of a large, strongly chitinized, roughly semi- 

 circular area, on the mid-posterior margin of which is situated the 

 vaginal opening ; this is protected by more or less complicated chitinous 

 folds which, within certain limits, are subject to considerable variation 

 in each species. The lateral margins of the vaginal plate are bent 

 over, forming a ribbon-like band on each side of the plate, the an- 

 terior ends of which usually approach each other on the mid-anterior 

 margin of the plate, the posterior ends tapering gradually to a point 



