78 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xn, 



FAMILY CHARACTERS. 



Imago. — Head not prominent, of moderate size; front shorter than in Saturniidse, and a 

 little wider; squamation shaggy, hairs in front rather long and irregular, and converging to a 

 blunt point in front; eyes of moderate size, in some genera (Hemileuca) rather small. Antennae 

 of male characteristic in shape, usually pectinated to tip, pectinations slender and long, giving 

 a subplumose appearance; the antennae rarely (Rhodormiscodes) subfiliform at extreme tip; 

 joints usually short, the basal pectinations long and slender and inclined to be curved down- 

 ward toward the end; distal pectinations varying in length and size, but usually half to three- 

 fourths as long as the basal ones; in Hemileuca maia, H. juno, Heliconisa and Pseudaphelia 

 no distal pectinations. Antennas of female either simple (Automeris) , subsimple (Molippa), 

 denticulate (Dirphia and Catocephala) or with short pectinations (Hemileuca subg. Euleuco- 

 pliaeus) or longer {Hemileuca maia and juno), so that the female antennas become nearly half 

 as wide as those of male, though the tips are subfiliform. 



Palpi 3-jointed, rather short, weak, not usually reaching the front, only in Dirphia reaching 

 to the front so as to be seen from above; third joint either short and not visible (concealed by 

 hairs of second), or visible but depressed; squamation loose, making them look bushy. 



Thorax rather large and shaggy, the hairs irregular, so that the prothorax and tegulas are 

 not distinct; in Dirphia and Ormiscodes these longer hairs are singularly modified, flattened, 

 slender, paddle-shaped, black and light. 



Legs with the femora very hairy; tibiae and tarsi usually thick; a tibial saclike appendage 

 in male Heliconisa, slender, about three-quarters as long as the tibia, but not yet detected in 

 other genera; in Pseudaphelia a large brown naked sac as long as, and wider than, the fore tibia, 

 arising at base. In Hylesia the entire fore leg to subtarsal joint is very hairy. 



Fore wings short and broad, triangular or narrower, about twice as long as broad; costa 

 nearly straight, and either arched or (Hemileuca) slightly concave; fore wings either not falcate 

 (Catocephala., Dirphia, Ormiscodes), or subfalcate (Molippa, Automeris, Heliconisa), or decidedly 

 falcate (Hylesia). 1 Hind wings broad and rather large (Dirphia) or subtriangular (Hylesia); 

 either not reaching to end of abdomen (Catocephala) or reaching to end (Automeris) or extending 

 beyond (Dirphia). 



Venation [no description]. 



Markings: Ocellus in fore wing, none in more generalized genera (Molippa, Dirphia), a 

 small discal spot (Catocephala, Ormiscodes), diffuse and indistinct (Rhodormiscodes, Hylesia, 

 Automeris), a round spot inclosing a reniform or crccentiform mark (Hemileuca) or none at all 

 (H. [Meroleuca] venosa). It appears on under side in Automeris. [In male A. io the large round 

 black spot on under side has a white pupil, which is often bright and very distinct.] On the hind 

 wing there is no ocellus except in Automeris, and a slight one in Hemileuca maia [and other 

 species of Hemileuca]. 



Abdomen large and full, variegated, beautifully banded in Molippa and Dirphia, and with 

 long scattered hairs. 



Larva.— Head round, body cylindrical; anal legs of moderate size, smaller than in Sphingi- 

 campidas and Saturniidas, being more generalized. Body not provided with high tubercles 

 giving rise to spines, but the spines are long and slender, branched in Dirphia and Automeris, 

 and arise from a slight eminence, on the skin. 



The eighth abdominal segment bears a median tuft, larger than those on each side, and 

 there are no generalized types (showing two separate ones). All hcwe the lateral eversible sacs, 

 a family character. 



There are two series of larval forms: 



(1) Dirphia to Automeris: With single long slender branched spines as in Dirphia, varying 

 in Automeris; with single and unbranched, or with branches (A. nyctinene from Brazil), or high 

 and much branched (A. pamina), or shorter and closer (A. io). 



(2) With smaller shorter collections of separate spines forming fascicles, as in Hemileuca, 

 Coloradia and Pseudohazis; the latter group appearing more specialized. 



1 [Strongly falcate in male ot Automeris auleles (Herrich-Schaeffer)). 



