168 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xii, 



on the third thoracic segment. The prothoracic dorsal tubercles each bear four curved setae, 

 while the second and third thoracic tubercles each carry six setae. The abdominal tubercles 

 are nearly as long as the thoracic ones, but much slenderer, and they are rather high, contract- 

 ing in diameter in the middle; they each bear two or three long curved black stiff bristles, 

 and two minute ones, the long ones being curved backwards, and before the larva has begun 

 to feed they are longer than the body is thick, so that it appears to be rather thickly clothed 

 with fine black bristles. 



The single median dorsal tubercle on the eighth abdominal segment is a third thicker than 

 the others in front, bearing three long black setae on each side. 



The two dorsal tubercles on the ninth abdominal segment are quite large, larger than 

 those on abdominal segments 1-7. Two dorsal tubercles arise from near the middle on each 

 side of the suranal plate; they are only a third smaller than those on the ninth segment; around 

 the edge of the suranal plate arise long grayish stiff straight hairs, and the bristles on each 

 lateral tubercle are grayish and directed downward. 



The body is dull straw-yellow on the sides and black above. The wide black dorsal band 

 is irregular in width, varying at the end of the stage. 



It gives off on each side behind the middle a straight black rectangular line forming a 

 black half-ring extending down to near the spiracles; the hinder edge of each segment is black. 

 The color variations of the larva in this stage are marked; in the most extreme the entire upper 

 part of the body is black below the spiracles, the black pigment extending down from the main 

 mass to the infraspiracular tubercles, the under side only of the body being yellow. There is 

 low down on the side of the body a narrow worn somewhat broken black line, situated below 

 the infraspiracular tubercles. Spiracles small, inconspicuous, black. Thoracic legs black ; abdom- 

 ianl legs in general yellow, when freshly hatched black, the planta slightly purplish livid. In 

 this stage the larva is very pretty and interesting, but with the true Saturnian shape of body 

 and tubercles. They molted May 24 or 25. 



Stage II: Length 12 mm.; toward end of stage 18 mm. Now very different from stage I. 

 The body is pale straw-yellow, and no black on it hi my examples (while one of those reared 

 by Mr. Joutel is black on the sides and on the first, third thoracic, and eighth abdominal seg- 

 ments, and he found that there are all stages from the wholly yellow to the dark form). 



The head is smooth, pale-green, black behind the eyes, the black extending up toward 

 the back of the vertex; it is nearly as wide as the first thoracic segment, which is considerably 

 narrower than the two following. The tubercles are now more prominent and are green and 

 pale turquoise-blue. The four dorsal ones on the first thoracic segment are well developed 

 and higher than before, the two middle ones nearly a quarter larger than the outer ones, each 

 bearing six stiff straight black setae. The spiracular one is pale turquoise-blue, as all the others 

 of this series to the end of the body. The two dorsal tubercles on the second and third thoracic 

 segments considerably (about one-sixth) larger than those on the abdominal segments and 

 those on the third thoracic considerably larger than those on the second segment; they each 

 bear eight black stiff setae, seven on the crown with an eighth in the center; these are yellowish 

 at base, beyond turquoise-blue; in the examples I bred the tubercles on the second thoracic 

 segment were green. The setae on the thoracic tubercles are not more than a quarter larger 

 than the tubercle itself. All the dorsal abdominal tubercles are green (or yellowish green, 

 Joutel), bearing each four black stiff and straight setae, one of them being usually small; the 

 longest setae are about one-third longer than the tubercle itself. The dorso-median tubercle 

 on the eighth abdominal segment, unlike all the other abdominal ones, is turquoise-blue; it 

 is fully twice as thick as those on the seventh segment. It does not show its double origin 

 as there is a central seta, and one behind it on the median line, with three on each side of the 

 two ; they are not arranged on each side of the median fine. 



On the side low down are two or three, minute black dots below each of the turquoise- 

 blue tubercles of the lowest series. 



Suranal plate and its tubercles pale straw-yellow, concolorous with the rest of the body, 

 with a large black roundish spot in the center. In those reared by Mr. Joutel, the two tubercles 

 on this plate are turquoise-blue. Spiracles black, fairly conspicuous. Anal legs green, centered 



