MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 101 



of the two on the eighth segment, and armed with white spinules. The suranal plate bhick: it 

 i,s rounded with six blaek and several white spines, the basal black ones the hirgest. The skin is 

 of a peculiar blackish pitch\- color. Spiracles black, with a narrow white line around them. 

 The thoracic and aVtdominal legs are dark pitchy, the latter sometimes very dark red with a snr- 

 plantar black patch; sides of the anal legs reddish, like the suranal plate; in other larva? the anal 

 legs are entirely black. Ho sithdorml or lateral pinkish stripe, lih' those in A. viryiniensis. 



One observed just molting from stage III. Brunswick, Me., July 27; a few minutes after 

 exuviation the body was still of the same dull chestnut red as in stage III (though the white gran- 

 ulations show that it is in stage IV). One (the left) horn is shorter than the others. The spines 

 are now all pale livid, as also the suranal plate and the anal legs. The thoracic and mid-abdom- 

 inal legs are pale testaceous. In one hour it became dark and the spines black. Five more 

 larva' had molted by July 31. (Compare PI. L. 2c. 2d; LI, tig. 2c; LII, tig. 3c.) 



St(t(/e V. — Length, 35 mm.; of the second thoracic dorsal spines, ti..5 mm. The head is of 

 the same cherry red color as in the previous stage. The second thoracic spine is about as long 

 as the body is thick and recurved; the other spines are more curved backward and downward 

 than in the previous stage and their shape is very ditJ'erent, the upper surface being smooth, the 

 spinules being collected on the under side; the usually single large spine being white and beyond 

 the middle, with smaller abortive spinules on the side; these spinules are larger on the spines of 

 the eighth and ninth segments. Suranal plate reddish, its surface rough, with white piliferous 

 granulations; near the base is a large black spine on each side, and two black ones of about the 

 same size at the end, forming a fork; the entire tenth abdominal segment reddish. Spiracles 

 black; a faint duskj-, spiracular line. Thoracic and abdominal legs pitchy black; sides of the 

 anal legs reddish. Skin dark, with more numerous white granulations than in the previous stage. 



It is quite different and easily di.stinguished from A. virghdensix; compared with this 

 species, the head is of the same size, Ijut tlie color quite different, being duU cherry or Indian 

 /¥'/, while that of A. virc/iniensis is j-ellowish amber and usually green. All the spines are much 

 longer; those on the back of the second thoi-acic longer, and those behind two or three times 

 longer; that on the ninth abdominal certainly three times as long as in' A. virgi?iiensis. The skin 

 is blacker, and thus the granulations are more distinct, besides being larger, while A. stigma 

 lacks the distinct suhdrimal and lateral pinJc or jlesh-colored hands present in A. virginiensis. The 

 spines on the suranal plate are stouter and longer. 



Stage YL — Some specimens reared at Brunswick. ]\Ie.. again molted July 3(i-31. The 

 following description was drawn up Augu,st 1 : 



Length. 37 mnj.; width of liead, 4.5 mm. It differs from tliose in stage \' in tiie liody l)eing 

 dark, dusky chestnut and denseh^ covered with porcelain-white granulations of uneven size. 

 There is no lateral paler line such as is seen in the previous stage. 



The horns are now less spiny, and all the horns and spines are shorter than in stage \ . The 

 spiracles are larger and with an outer white ring. The head, thoracic legs, and tenth abdominal 

 segment are reddish or pale chestnut. 



Two were observed moving their heads from one side to the other on being disturbed. 



The following notes by liiley are added from my Forest Insects, page I'itj: 



■■ Yoang larra. — August 24, 187(), found a lot of caterpillars feeding on Quii'cus hi color? 

 The}' are 0.63 of an inch in length, and of a dark greenish-gray color, with a broad dorsal line a 

 shade darker; on each segment there are six black thorns tipped with white; two on the dorsal 

 line, one on each side, and one oi»the margin of each side; those on the sides are very small and 

 more like tubercles; thorns on the back and sides nearly equal in length, getting a little Iong(>r 

 on the last segments; on the second segment are two very long horns, resembling very nuicli 

 antenna', the point of which is divided into two; they are directed forward and curved a little 

 backward. Head brick-red. not very glossy; feet black. Destroyed by parasites. (Riley's 

 unpulilished. notes.) 



" Full grown larra. — Average length .)0 nnn. (ieneral color pale tawny-red. inclining to 

 orange. The whole surface covered witii bright yellow, almost white papilhe of different sizes, 

 giving a speckled appearance; the usual medio-dorsal narrow line; abroad subdorsal longitudi- 



