MKMOIKS OF TlIK NATIONAL ACADEMY OP^ SCIENCES. 59 



poctinatioiis rine, slonder. Hat, and closely pressed to the hasal branches of the next joint. (This 

 type of antenna^ is ver\- persistent, with no exception; those of 9 , either with a sini^le pair of 

 stout, siiort pectinations (AdiJoct'jiliala hicolor)^ or simple, witliout vestijj'ial branches (Anisota, 

 Adelocephala. Syssphinx, Eacles, and Cithcronia, except in I'. j)i'!ncljH(lis, in which the}- are 

 minute, teeth-like). 



Palpi usually much i-educed; in Adclocoj^hala scarcely visible, short, f(^eble, depressed; 

 where largest and best developed, not rcachin<j' the front (Eacles and Citheronia); deiuxded, 

 3-jointed (Anisota, PI. XXXVl, tigs. 1<), 10a); iu Eacles, 2-jointed (fig. 11). 



MaxilliV varying in degree of development even in the same genus; not united to form a 

 sucking tube; in Anisota, apparently no vestige left; in AdvlocephaJa suhaiigalata, they are 

 comparatively well developed, and are as long as the filiform tip of the antennas in Eacles, 

 longer than in any other genus, l)ut not visible without removing the scales; in Citheronia, as 

 long as the front of the head in the middle (PI. XXXVI, fig. 5). 



Bod\- Sphinx-like, or spindle-shaped, thick; thorax stout; abdomen lai"ge and rather long. 



Fore wings usually narrow. Sphinx-like in shape in Sj'ssphinx and manj^ species of Adelo- 

 cephala. The costa straight, apex acute, the outer edge very oblique; either simple or scalloped 

 (as in Smerinthus), the inner angle nearl}- effaced; or the wings become wider, the costa more 

 arched toward the apex, which tends to become square and the outer edge less oblique in Eacles 

 and Citheronia, those of Anisota being intermediate in shape. 



Hind wings also sphingoid in size and shape; short, very broad, and not reaching so near 

 the end of the abdomen as usual; in Adelocephala and Syssphinx the costa very full, convex; 

 apex rounded, outer edge somewhat excavated in $ or, as in S Anisota, of a singular triangular 

 shape, somewhat produced toward the inner angle; this characteristic especially emphasized in 

 A. virginiensis. The hind wings are most normal or conventional in shape in Eacles and 

 Citheronia, where the outer edge of the wing is full and rounded. 



Venation: Fore wings, eleven veins present; the discal cell smaller than in any other 

 subfamily of the protosphingoid group; it is only about one-third as long as the wing, and very 

 narrow, especially in Adelocephala, Syssphinx, Anisota. and Citheronia. 



Vein IV2 (or sixth radial) forming a true independent vein, being widely detached from 

 its stalk, and situated in the middle of the extradiscal cell, i. e., just midwaj^ between veins IV, 

 and IV3. This lilieration or detachment of vein IV„ is most marked in Eacles, but less so in 

 Citheronia, j^et the character is very persistent and fairl}- diagnostic, as much as anj' character 

 can be. 



The two discal veins taken together form an oblique line, which is directed outward in 

 Eacles, the posterior discal vein being directed inward in Citheronia, while the line is straight 

 in S^'ssphinx; in Adelocephala Msecta and suhangulata the line is regularl}^ curved. The course 

 of these veins is peculiar and characteristic of the group in Adelocephala, Sj'ssphinx, Anisota, 

 and Citheronia. 



Hind wing: Vein II (subcostal + radial vein) is almost sinuous in Syssphinx. There are 

 invariably nine veins instead of eight (not counting I) (a diagnostic feature), this being the addi- 

 tion of vein VII; VIII being the second axillary vein. The discal cell very small; especiall}' 

 narrow in Adelocejyhala hisecta. The discal veins taken together form an oblique line, which 

 is curved outward, especially in Eacles. 



Vein IV,, only partially detached, never forming a true independent vein, thus differing 

 from the Agliinse (though Aglia itself approaches Eacles in the venation of the hind wings). 



Legs long, stout, strong, spined, the vestitui'e short and close, nuich as in Sphingid;e. The 

 fore-tibial epiphysis well developed, varying in shape from lanceolate to oval. (PI. XXXVI, 

 figs. 12-22.) 



Larva. — Body sphingiform, anal legs like those of the Sphingidiv; head subconical, narrow- 

 ing toward the vertex; the surface smootli, not linelv spinulated with secoiidarj- spinules as in 

 SmerinthiuK. The trunk segments armed with long, sharp, dorsal and subdorsal curved spines, 

 those of the pi-othoracic segment sometimes well developed (in the more primitive species of 

 Adelocephala and Citheronia), but usually partially atrophied. A long, sharp caudal horn; 

 between this and the thoracic horns the dorsal spines of abdominal segments 1 to T in tiie more 



