1893.] Ibb [Packard. 



dominal spiracle is a bicolored stripe ; it is pure marble-white below, and 

 above rosy purple, and is interrupted by tlie wax-colored spiracles, which 

 extend above the upper limits of the reddish line. The suranal plate is 

 very large and long, deeply divided at the end, the two forks being, like 

 the surface, coarsely granulated with stout short conical spines ; the plate 

 is green, with the edge straw-yellow. There is a minute median spine 

 on tlie ninth abdominal segment. Each abdominal segment with two 

 dorsal transverse rows of white, bead-like, coarse granulations. Below 

 the bicolored lateral stripe is a black, double, conical spine on each seg- 

 ment, and underneath on abdominal segments 1, 2, 7 and 8 is a group of 

 unequal, smaller, black, sharp spines. The body beneath is granulated 

 with white, and also on the sides, as well as above. 



The thoracic legs are black, partly greenish beneath ; the abdominal 

 legs, including the anal pair, are greenish, wilh a group of singular black 

 piliferous spines, while some of the spines are tipped with white. 



The general color of the body is of nearly the same hue as the under 

 side of the leaves of the honey-locust, and thus colored it is partly assimi- 

 lated and protected by its color, while the horns are in general like the 

 spines of its food plants. On the other hand the gleaming silvery spines 

 certainly render the creature conspicuous, as well as the lateral parti- 

 colored band. 



Tt would appear probable that the formidable spines of the grown-up 

 caterpillar save it not infrequently from being swallowed by birds ; 

 though the horns are probably of greater use in the earlier stages when 

 they are much longer and much more movable, in frightening away ich- 

 neumons and Tachinse. For example, even when 20 mm. in length, a 

 larva was seen when teased to spread apart its great arm-like horns, while 

 the full-fed ones did not notice such stimulus. 



SUMMAKY OF THE SALIENT FEATURES IN THE ONTOGENY OP SpHIN- 

 GICAMPA BICOLOR. 



A. Congenital Characters of the Larva; all appearing in Stage I. 



1. The two pairs of enormous spines of second and third thoracic seg- 

 ments one-half as long as the body, and ending in a two-spined, large, 

 flattened, dark bulb ; freely movable and plainly defensive in function. 



2. The large, reddish, spiny "caudal horn," on the eighth uromere, 

 ending in two bristles. 



3. The double piliferous tubercle on the ninth uromere ; becoming 

 obsolete in Stages IV and V. 



4. The abdominal region is longitudinally striped with dark and 



whitish bands, but there are no transverse marks in Stage I or in later 



stages. 



B. Ecolution of Later Adaptational Characters. 



1. The head slightly angular, face subtriangular, with a light brown 

 or greenish lateral stripe (Stages II-V). 



