1871.] 125 
pairs of rows, three of them above, one on a line with, and one below, 
the spiracles. In the mature form, the hairs have given place to stout 
tapering spines, each supplied with many aculiferous, conical wartlets, 
and arranged in a median dorsal series and four pairs of lateral rows, 
two above and two below the spiracles. 
If we next turn our attention to the Lycenide, we shall find 
similar differences. While the form of the head and body remain 
nearly the same from youth to maturity, the contrasts between the 
dorsal and lateral surfaces of the body are more pronounced in the 
early stage, both from the greater flattening of the upper field, and 
from the presence, at the line of demarcation between the two, of a 
series of warts, emitting hairs, some of which are exceedingly long, and 
curve backwards ; similar hair-bearing warts are present along the fold 
dividing the lateral and the ventral regions, while there are one or 
more longitudinal rows of simple warts along the sides. The different 
groups, the Thecle, Lycene, and Chrysophani, can be distinguished by 
the number of warts to a segment in each of the first-mentioned rows, 
and by the character of the hairs borne by them. In the full-grown 
larva, the linear series of warts are wanting, but the whole body is 
covered with microscopic hairs, seated, in Lycena, on stellate dots, and 
which are only slightly, if at all, longer upon the angles of the body. 
In the Papilionide, again, we find no differences of importance in 
the shape of the head, but some peculiar features in the armature and 
form of the body. In Colias, the embryonic animal is furnished with 
four rows of peculiar appendages on either side of the body, three rows 
above the spiracles, each bearing one appendage to a segment, and one 
beneath them bearing two appendages to a segment; these appendages 
are short, fleshy papille, expanding from a slender base to a club-shaped 
apex, as broad at its tip as the entire length. In the mature larva, all this 
is wanting, but the body is profusely clothed with minute short hairs, 
seated on regularly-disposed delicate warts. 
Pieris is similar; the young larva is furnished with long, hair-like 
appendages, tapering slightly, but at the tip expanding into a delicate 
club, and disposed much as in Colas. In the mature larva, the body is 
furnished with two sets of minute warts, one arranged in regular trans- 
verse series and hairless, the other irregularly distributed and emitting 
each a short delicate hair. 
In Papilio, the body of the infantine caterpillar is invariably more 
or less angulated, like that of the young Lycenid ; while, at maturity, 
it is always quite regularly rounded above the spiracles. It is furnished, 
when young, with several longitudinal rows of bristle-bearing tubercles, 
one tubercle to a segment in each row, one row in the middle of the 
side more conspicuous than the others. When full grown, the body is 
