226 MEMOIRS OF TUE 2JAT10XAL ACADEMY OF S0^E^'CE6. 



Third stuf/e. — Lciistti, lU-l-"> mni. Tlic cliariU'ters of the (inal stage now appear. The head 

 bas changed its shape and style of iuarkin};;s to tliat of tlic last stag;e; it is flatter in front, with 

 a lateral brown line edged with white, while the large, conspicnous, dark spots Inive disa])i)eared, 

 and the color of the head is dull opa(|iieaniber. The four red, parallel, dorsal lines on the second 

 and third thoracic and seventh and eightii abdominal segments are now distinct. All the dorsal 

 tubercles except those on the prothoracic and lirst and eighth abdominal segments have much 

 diminished in size, while the others have remained stationaiy. 



Fonrtli stdijc. — Length, IS mm. The i)iliferous waits in general are smaller than in Stage III, 

 and those on tlie protiioracic and lirst and ciglitli abdominal segments are smaller tlian lieiore. 

 The eighth abdominal segment is slightly humped, and the anal legs are normal, though about 

 one-half as thick as those in front. Tiie body is green, with a broad subdorsal and two nanow 

 lateral yellow lines, as in the last stage, the lower being tlie infraspiracular line. The sides of the 

 three thoracic segments are dotted with reddish pink, and there is a reddish streak on the outside 

 of the anal legs. The subdorsal yellow lines diverge on the prothoracic segment, and along the 

 next two segments suiH-ceding are edged within with piidc red lines. Behind the two dorsal 

 tubercles ou the lirst abdominal segment they are much farther ai)art, extending to the sujjraanal 

 l)late, and are whitish yellow, narrowly bordered with deep, straw-yellow, and inclose a narrow, 

 yellow dorsal line. (This line in the next stage extends to the i)rothoracic segment.) 



Fifth and lant stuije. — Length, 3(t-.'$li mm. It differs in the dorsal jiiliferons warts on the lirst 

 thoracic and first and eighth abdominal .segments being smaller than in the fourth stage, being 

 now no larger than those on the other segments, and the hump on the eighth seguuMit has almost 

 disappeared. There is, as in the fourth stage, a conspicnous red dash on each side of the third 

 abdominal segment, and the other lines are as described in the fourth stage. 



IIKCAI'ITULATION. 



1. Head large, with dark spots aiul connected lines in Stages I and IT. 



2. The si)()ts disapi)ear, and the peculiar lateral dark line edged with white characteristic of 

 the final stage apjiears in Stage III. 



3. The piliferous tubercles on first thoracic and first and eighth abdominal segments attain 

 their maximum in Stage II; the tendency after this stage is to return to a simple, smooth body, 

 without excessive ornamentation or any decided change in coloration. 



4. In Stag<' irr all the other tubercles diminish in size. 



.j. The style of coloration of Stage V is indicated in Stage II. 



C. In Stage IV the tubercles almost reach their minimum, beconung still smaller in the final 

 stage. 



7. The few tenant hairs present in the first stage are battledoor-shaped. 



It is interesting to notice, in reviewing the larval history of this species, the strong tendency 

 shown after the second stage to a diminution in size of the tubercles, so that by the fourth stage 

 the body becomes smooth and free from all projections, humps, and spines, and thus more 

 uoctuiform. At the same time the yellow and whitish stripes and i)ink blotches beconu^ indicated 

 at an earlier stage than usual, as if the aim were to adaiit the caterpillar to the ribs and parallel 

 greenish and yellowish lines or shades of the leaf on which it feeds. 



This is ]»eriiaps, as regarils the other species, liie most generalized and simple form in its 

 early larval stages, there being no horns and the dorsal warts of nearly uniform size. 



In the group comjjrising II. hiundata, (lutticitta, and obliqua there is a singular degree of hyper- 

 tro|)hy and s])ecialization of the dorsal tubercles, while in the group represented by //. »;//(•«/(>;• 

 the process of hypertnjphy and specialiicatiou takes another direction, i. e., the anal legs, the lar\a' 

 becoming ceruraform. 



RI':m,vuk;s. — PI. XXIX, (igs. 2, 2n re])reseut what may prove to bo the young larva of this sjn'- 

 cies. It was found l)y Mr. iiridgliam on tlie walnul at Prcjvideiicie, U. 1., July ."». I have no notes 

 on it. The following deseri[)tioiis have been drawn up from Comstock's specimens, the types of his 

 description in his report as United States I<jnto;no]i)gist for ISSO. His Xo. L'l!>. " Notodonta on 

 oak, September 23, IST'J,'' is eixual to var. v. of his description. I am indebted to Professor liilcy 



