60 PROCEEDINGS OF THE AMERICAN ACADEMY 



Figure 2 (Plate I.) represents the last three abdominal segments ; 

 VIII. bearing the median double tubercle d', and IX. the 9th pair 

 (the right subdorsal tubercle on the 9th segment not being drawn) ; 

 X. the suranal plate with its armature, the two lateral tubercles, 

 bearing each six seta?; the tubercles in front usually bear five setae. 



Figure 3. The double median dorsal tubercle of the 8th abdominal 

 segment, showing a light median furrow, the probable line of union of 

 what in the embryo were originally separate tubercles ; it bears ten 

 setse, arranged in two lateral groups of five each. 



Stage II. — (Described one or two days after moulting.) Length 

 14 mm. The head now is quite small, scarcely one half wider than the 

 body ; it is entirely black. 



The body is dull dusky livid greenish ; the tubercles are somewhat 

 yellowish at base on the conical portion, but the slender chitinons por- 

 tion is shining black, and the radiating bristles are all black ; one or 

 two of them are longer than the column or chitinous portion of the 

 tubercle. Tlie thoracic tubercles are slightly longer than those on the 

 abdominal segments, and the single median one on the 8th abdominal 

 segment is slightly larger than those on the 7th and 9th segments, 

 and is now about twice as thick as those on the side, and bears eight 

 bristles, the lateral ones on the same segment bearing five. The pro- 

 thoracic segment is a little darker than the others ; it bears a chitinous 

 black plate about four times as broad as long, bearing on the front 

 edge four setiferous tubercles of equal size, one at each end, and with 

 two yellow spots. The tubercles in general are now long and slender, 

 with a conical base, the stalk contracted and rather slender in the 



