2 
Journal New York Entomological Society. 
[Vol. IV. 
Special Structural Characters. 
Dorsal and lateral spaces broad, subventral space narrow, con¬ 
tracted. Ridges very slight, the subdorsal indicated only by the change 
in direction in the slope of the body, lateral and subventral ridges more 
distinct, approximate. The ancestral warts converted into fleshy 
horn-like processes, unequally elongated; in stage I bearing a few 
slender setae (Plate I, fig. i); after the first molt, the subdorsal and 
lateral rows covered with numerous urticating spines, the subventral 
row rudimentary, represented by two weak setae. Of the subdorsal 
row, the “horns” on joints 3 to 5 and n to 13 are distinct, those on 
joints 6 to 10 rudimentary, but a seta is present even in the last stage. 
Of the lateral row, the one on joint 5 is absent. 
Depressed areas very feebly developed, only their glandular cen¬ 
ters distinguishable as slight pits, partially free from skin spines; the 
dorsal row (1) consequently paired, the addorsal row (2) still slighter, 
only distinguishable on certain segments or at favorable times, such as 
just before a molt. Of the lateral rows, the lateral (4) and lower inter- 
segmental lateral (6) can be made out as slight pits. No others visible. 
In the contracted subventral space, the two large rows (7 and 8) appear 
as faint glandular dots, nearly in line. Skin at first smooth, in the 
later stages finely spinulose. 
At the last molt, besides certain changes in color, the length of 
the “horns” is markedly reduced and their skin-spines shortened. 
Certain highly modified, easily detachable skin-spines appear, the 
shorter ones, designated “caltropes” by Dr. Packard, occur in patches 
at the ends of the horns of the lateral row on joints 6 to 11 ; the long 
ones arise from four circular areas of the skin at the posterior end of 
the body between the terminal horns, and correspond to the cal trope 
patches of the lateral horn of joint 12 and the subdorsal one of joint 13, 
which bear the true caltropes in the lower forms of our “larvae of type 2.” 
The coloration is bright and conspicuous, being probably of a 
warning nature connected with the defensive armor. It is of a peculiar 
and striking pattern, which doubtless aids in the effect produced. 
The larva is a generalized one in the slight degree of retraction of 
joint 2; the presence of many-spined warts; the slightly marked ridges 
and poorly developed skin structure. It is specialized in the unequal 
degree of prolongation of the warts on the several segments, the wart 
of the lateral row on joint 5 being entirely suppressed, while the spir¬ 
acle on that segment is moved up out of line with the others; in the 
