64 PROCEEDINGS OF THE AMERICAN ACADEMY 



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 8th 

 abdominal tubercle are much shorter and stouter than before, as are 

 all the spines on the other tubercles. 



In all the five larvae, 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 ten dorsal 

 black rounded spots, two on a segment, along the abdomen * 



On the inside of the base of the infraspiracular row of turquoise- 

 blue tubercles is a black spot, wanting on the 3d thoracic, but present 

 on the 2d thoracic tubercle. 



Recapitulation of the more Salient Ontogenetic Features. 

 A. Congenital Characters. 



1. The setae 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 S. 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. 



* This larva wants the right 3d thoracic tubercle, and also the right 2d 

 abdominal one. In another larva of the same stage the right 1st 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 S. cynthia and T. polyphemus. 



