216 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xn, 



The thoracic legs are black; those of the abdominal region green, but shining black on the outer side; the anal 

 legs with a shining black patch nearly covering the outside of the leg. In one example the tubercles are aborted on 

 the left side of the second and third thoracic and the first abdominal segments. 



Stage IV. July 12, one had just moulted, the end of the body having just been withdrawn from the cast skin at 

 11.10 a. m. Length 25 mm. The head and prothoracic segment are green, while all the prothoracic tubercles and 

 those of the subdorsal and infraspiracular rows are a beautiful pale cobalt blue. The two dorsal tubercles of the 

 second and third thoracic segments are deep orange (afterwards becoming coral red); the homologous dorsal abdominal 

 ones, including the single median one on the eighth segment, are lemon yellow. The body is tinged with blue, 

 especially on the thoracic segments. The spiracles are white with a fine black circle, and contain a straight linear 

 central mark. All the bristles are still long, radiated, and are black. 



In this stage the four dorsal tubercles of the second and third thoracic segments are larger than any others on 

 the body; and those on the first seven abdominal segments are of nearly uniform size; the single one on the eighth 

 segment being nearly twice as thick. 



In this stage the 8 to 10 black dorsal and lateral spots dwindle in size, becoming less conspicuous; but the 

 black spots on the side of the head and on the sides of the abdominal legs are large and distinct. 



Stage V, and last: Length 40—15 mm. One which molted about the 9th of July had a pea-green head and pro- 

 thoracic segment; the head marked with a roundish black spot on each side, below which is a large black patch 

 bearing the ocelli, and lower down a black spot. The body is pea-green, washed ■with cobalt blue along the back, 

 beginning with the second thoracic and ending with the eighth abdominal segment, and the black spots along the back 

 and sides have disappeared. Of the lowest lateral row of five small tubercles, the three thoracic and those on the first 

 two abdominal segments are black; those on the third and fifth are blue at the end, but the bristles are black. All 

 the prothoracic and the two rows of lateral (the subdorsal and infraspiracular) tubercles are cobalt blue. The two 

 dorsal tubercles of the second and third thoracic segments are deep coral red; the corresponding ones on abdominal 

 segments 1 to 7, and the single one on the eighth segment, are lemon yellow. 



The spiracles are now white with a narrow black ring, but no central dark line. The thoracic feet are green, but 

 black at the end. The black spots on the sides of the pea-green abdominal feet are noio obsolete; the plantse are bluish. 



July 25-26. Some individuals were observed while molting into the last stage, their length after exuviation 

 being 47 mm. ; they became after feeding still larger. This stage differs from stage IV in the tubercles on the first 

 abdominal segments being much larger and more spherical than before, and orange rather than yellow, and thus in size, 

 color, and the spines being more like the four coral-red thoracic tubercles than the other dorsal abdominal ones. 



On the first abdominal, as well as the thoracic round-headed tubercles, there is a circle of eight black flattened knobs 

 representing the circle of spines above at the end; also the black spines on the median eighth abdominal tubercle are much 

 shorter and stouter than before, as are all the spines on the other tubercles. 



In all the five larvse, except one, and in those of both stages (IV and V) the rows of black intertubercular spots 

 have disappeared, the one retaining them (40 mm. long) having a single row of 10 dorsal black rounded spots, two on 

 a segment, along the abdomen. 1 



On the inside of the base of the infraspiracular row of turquoise-blue tubercles is a black spot, wanting on the 

 third thoracic, but present on the second thoracic tubercle. 



Recapitulation of the more Salient Ontogenetic Features. 

 A. Congenital Characters. 



1. The seta? in stage I blunt, slightly bulbous, and glandular. 



2. The tubercles are all of the same size. 



3. Body in stage I dark, almost blackish, green, head jet-black; tubercles yellowish green. 



4. The homologue of the "caudal horn " shows plainly its double origin. 



5. The difference between the colors of the larva of the first and last stages very marked. 



B. Evolution of later Adaptational Features. 



1. The thoracic dorsal tubercles in stage II and onward are longer than the abdominal ones. 



2. Five rows of indistinct black spots along the body in stage II not so distinct as in P. cynthia, the body being still 



dusky green. (These do not originate from lines.) At the end of stage II the larva is more like cynthia of the 

 same age, the body being more yellow, and the black spots more distinct. The spots disappear at the end of 

 stage IV. 



3. The thoracic dorsal tubercles deep orange; their homologues on the abdominal segments amber-yellow. 



4. The tubercles at the end of stage II and in stage III spotted on the sides with black. 



5. In Btage III the dorsal tubercles of second and third thoracic segments showy coral-red. The subdorsal and 



infraspiracular tubercles tipped with pale blue; in stage II the same tubercles are almost entirely pale blue. 



6. The head becomes green in stage IV, with a black spot on the side. 



1 This larva wants tho right third thoracic tubercle, and also the right second abdominal one. In another larva of the same stage the right 

 first abdominal tubercle is partly atrophied, half the normal size, and with only two or three rudimentary spines. These tubercles and their 

 spines in confinement are apt to be atrophied from disease; this also occurs in P. cynthia and T. polyphtmus. 



