MKMOIIJS OK TlIK NATIONAL ACADEMY OF SCIENCES. 27 



pale reddish but imicli paler at base; the caudal horn nuu-h paler than the thoracic ones. 'J'hei'c^ 

 is a black ring- around the bas(> of the thoracic legs.. The spii-aeles are deep purple around the 

 edge, those of the eight a))douiinal i)air darkest, becoming paler toward the first segment; the 

 prothoracic ones only partially stained with jiurjile. In Hi'idghain's drawings the spiracles are 

 drawn with a blackish ring (PI. IX). The niidabdominal l(>gs are dusky brown at base, and 

 the planta> blackish. The anal legs or claspers and also the suranal plate are yellowish, but 

 black in the middle area, though the granulations are yellowish. The head has a rlark short 

 line on each side, and two diverging dark lines on each side of the clypeus. 



St(n/i> }'(f<i.if). — A blown specimen is uniformly deep pea green, with no lirnwu siiadc. The 

 head is as in Stage lY, but green ])ehind the yellowish fi-ont. The spines are yellow, with no 

 red discoloration on them. The spiracles are deep purple, and do not become paler anteriorlj-. 

 The}' are drawn bluish purple" by Mr. Bridgham (PI. IX). The suranal plate and anal legs are 

 identical in coloration with those of Stage l\ . 



The hi'oicnforiii. — I will first describe a fully grown blown example of the same size and 

 shape as the above-described green larva. The body is reddish r)rown; ^yith three paler, clearer, 

 subdorsal dili'use ii'regular patches on each segment, forming two obscure broad interrupted 

 longitudinal bands. The region about each spiracle is also paler brown, forming an oblique oval 

 patch, passing from the front edge of the segment downward. The pale j'ellowish spiracles are 

 verj- conspicuous and are surrounded ])v a dark purple ring. The spines are fully as stout as in 

 the green form, and the l)ody is e(iuall3- hairy, the hairs being whitish. The head differs from 

 that of the green form in the greater amount of dark ))rown, both on the sides and along the 

 middle in front, yet the back part of the sides, that corresponding to the green portions in the 

 green larva, is dull obscure yellowish. The colors of the suranal plate and of the anal legs are 

 much as in the green form, but a greater extent of the anal legs is black-brown. The thoracic 

 legs are yellow, but the midal)dominal ones dark lirown. 



St(t(je IV. — It ditlers from the green one of this age in being bright reddish, the tubercles 

 of the same hue, while the head is reddish, as are the legs, thoracic and abdominal, while the 

 edges of the suranal plate and anal legs are tinged with reddisli. The spiracles are surrounded 

 by a brown ring. 



A third form, a true dimorphic form, appears to be that represented on PL YIII, fig. 6. I 

 will describe a specimen received ))v exchange from the nuiseum of the Brooklyn Institute. It 

 ditlers structurally in the slightl}' stouter tubercles and denser hairs. In color it differs from the 

 brown form aliove described in being of a rich, dark umber or Yandyke brown. The subdorsal 

 row of pal(> sienna brown patches is more distinct, and the sei'ies is made up of a single large 

 S(|uarish patch, situated on the fi'ont edge of each segment, except the prothoracic and the ninth 

 and tenth abdominal. The spiracles are conspicuously straw-yellow with a luown ring (I can 

 detect no purplish hue in the dried specimen); the oval oblicjue patches inclosing them are of the 

 same hue as those on the tergum, and also those of the brown form. The head (PI. YIII. tig. 6^/) 

 is nearly all black-brown on the sid(>s and in the middle, leaving an irregular yellow band on each 

 side of the front: the anterior clypeus and labrum are also yellowish or luteous. The suranal 

 plate is dark brown, as are the anal legs, except the front edge of the legs, which are yellowish; 

 the secondary tubercles or granulations are yellowish. The thoracic legs are yellow and lilack; 

 the niidabdominal ones brown-black. The tubercles are all l)lack-brown. 



T/ii' three color forinx (if CitJteninta rrgalis. — Mr. A. Hyatt Yerrill has called my attention to 

 .some striking color variations of this caterpillar, of which he took photographs in color somewhat 

 touched up by hand. The variations are in green, green and orange, Ijlue, and brown. My 

 n(jtes are taken from his colored photographs as I have not yet had the fortune to see the larva 

 of this species while alive. 



In all the forms the size, shape, and colors (orange, red, and l)lack) of the spines are the same, 

 as also the color of the head, thoracic and abdominal legs, and the suranal plate. 



« In the plate, however, they are unfortunately printed black. 



