Packard.] 
502 
[Feb. 19, 
tain, but probably from what Weismann has concluded from his 
studies of the Sphingidse, the subdorsal arose first. In the second 
stage of Spilosoma virginica, the subdorsal lines are reddish lines 
extending between the two subdorsal rows of alternating subdorsal 
piliferous warts ; the line becoming more decided however in the 
third stage of this species, there being as yet no signs of a spiracu- 
lar or of any lateral line. In the freshly hatched larva of H. textor , 
however, what may be the first beginnings of the subdorsal line are 
elongated brownish linear spots enclosing the subdorsal row of larger 
piliferous dots, but not reaching the sutures between the segments. 
These patches, however, do not in the second stage unite to form 
continuous lines, but two rows of decided black elongated spots, 
enclosing the black piliferous tubercles. In the freshly-hatched larva 
of Edema albifrons each of the two subdorsal lines is a row of elon- 
gated black spots connected on the three thoracic segments, but 
separated by the sutures along the abdominal segments. 
The spiracular line is seen in the same larva of the same stage to 
be a yellowish band enclosing the spiracles ; and there seems to 
be a tendency in some, if not many, larvae for the spiracles to be 
enclosed and connected by a parti-colored or bright line, and for 
this to have a darker (as in Edema) or lighter edging. Why the 
spiracles themselves are so apt, as in Bombyces and Sphinges, to 
be enclosed by a dark or conspicuous line remains to be explained. 
To return to the subdorsal lines in the pale reddish larva of Da- 
tana, probably D. integerrima , these lines before the first moult are 
also enclosed by the two rows of subdorsal piliferous spots, and in 
both the first and second stages there are pale spiracular lines, which 
appear to be contemporaneous with the subdorsal line. In the third 
stage a new dark red line is interpolated between the subdorsal and 
spiracular. In the fourth stage, the spiracular line has disappeared, 
and there is a supra- and an infra-spiracular pale line on the now 
brown dark skin of the caterpillar. Seen from above there are four 
pale lilac lines ; but after moulting two of them disappear and in 
the last stage there are only two subdorsal lines to be seen, if my 
colored drawings very carefully made by Mr. Brigham are correct. 
We thus see that after the subdorsal and spiracular lines are formed, 
others are rapidly introduced, and some may as rapidly vanish, as 
necessary features of certain stages, which when they become use- 
less are discarded. 
The admirable and most suggestive work of Weismann has 
