48 WILLIAM T. M. FORBES 



35. Sc strongly divergent from R at extreme base, then sharply bent and touching, 



fusing or closely parallel to it, or connected by a strong cross vein; tympanic 

 hood conspicuous, lateral A few Geometridae (p. 41) 



36. Antennae naked, or with a few fugitive scales on shaft 37 



36. Antennae closely scaled on upper side (figs. 9, 10) 38 



37. M! stalked with R in both wings or neither; hind wing usually with one anal 



(figs. 413-416); male antennae pectinate to apex Saturniidae (p. 668) 



37. M! stalked with R in fore wing but not in hind wing; hind wing with two anals 



(figs. 419, 422) ; male antennae pectinate halfway to apex. 



Citheroniidae (p. 664) 



38. Sc of hind wing sharply divergent from R from close to base (fig. 411) 39 



38. Sc and R parallel at base, connected by a weak crossvein (fig. 426) 41 



39. R^+s widely separated from R 8 all the way from cell to margin (fig. 411). 



Lacosomidae (p. 656) 



39. R arising from cell closely associated with R, 40 



40. R g and M t stalked or closely approximate at base, and separate from R! (like 



fig. 409) Uraniidae 



40. Ro separate from Mj (like fig. 414) Lonomiidae 



41. Frenulum about one -sixteenth length of hind wing; four radial veins in fore 



wing Eupterotidae (Eupterotinae) 



41. Frenulum obsolescent, not exceeding ] "meral angle, or absent, 5 radials. 



Bombycidas (p. 679) 



42. Cu, of fore wing arising from cell about a third way out from base, or even 



nearer base; RB stalked with M^; with humeral veins and without frenulum 

 in the North American species (fig. 427) Lasiocampidae (p. 679) 



42. Cu, of fore wing arising well beyond middle of cell; hind wing usually with 



frenulum 43 



43. Fore wing with complete venation (twelve veins) all the radials, medials, and 



cubitals arising separately, or with R, and R, shortly stalked (fig. 195). 



Tnyrididae (p. 521) 



43. R 3 and R, or R< and RB long-stalked, or with some veins absent 44 



44. Sc and R of hind wing parallel to beyond separation of R from cell, and then 



approaching very close or fusing a short distance (figs. 306, 435) 45 



44. Sc fusing to upper side of cell or wholly independent 46 



45. First segment of abdomen with chitinized subventral bullee, and a subdorsal 



cavity opening backward; northeastern species expanding over 25 mm. 



Drepanidas (p 688) 



45. First segment of abdomen not modified; northeastern species expanding 



less than 20mm .Pyralididae (Chrysauginae) 7 (p. 528) 



46. Sc apparently absent, fused except at extreme base with R. 



Euchromiidae (p. 43) 



46. Sc and R separating before end of cell 47 



47. Antennae swollen toward tip Agaristidae (p. 42) 



47. Shaft of antennae regularly tapering 48 



48. Ocelli present (fig. 3) 49 



48. Ocelli absent 53 



49. Sc and R of hind wing fused to middle of cell or beyond. .Most Arctiidse (p. 42) 

 49. Sc and R fused for more than a fifth length of cell, but the fusion not reaching 



middle 50 



49. Sc and R fused for less than a fifth length of cell, the fusion sometimes imper- 



fect 51 



50. Hind tarsus ordinarily not more than eight times as long as thick, tibia often 



with reduced spurs; M 2 reduced only in Eubaphe; in the rest of full strength 

 and associated with cubital stem; moths often stout; Sc very much swollen 

 at base ; hood above spiracle Many Arctiidae (p. 42) 



1 Also moat tropioa IThyrididse. 



