Packard.] 
552 
[Feb. 19, 
The anal legs are very long and slender closely resembling 
those of Cerura, about four times as long as the body is thick ; 
reddish beneath and at the tips, with a pale broad ring before the 
tip. 
Fourth stage . — Length of body 22, of the “tails” 8-9 mm. ; length 
just before moulting 28 ; of the “tails” 10 mm. 
Larva much as in the third stage ; the prothoracic tubercles as 
before, but slightly smaller in proportion to the body. The anal 
or filamental legs are as before, with the color and pale ring as in 
the stage III, the flagellum or everted portion nearly as long as the- 
sheatli, which is red at the end. 
Fifth and last stage . — Length 40-42 mm. ; furcula 4-5 mm. I 
have already briefly described the last stage of this caterpillar. 1 
A great change has occurred in the prothoracic tubercles which 
are now two low, flattened, inconspicuous warts on the upturned or 
flaring edge of the segment. The anal legs are much shorter in 
proportion and not so long as the body is thick, being about one- 
third as long in proportion as in the third and fourth stages. 
This caterpillar we have observed when disturbed to send out 
from near the head a copious shower of spray, or vapor, being in 
this respect like that of Cerura, so carefully worked out by Mr. E. 
B. Poulton. The opening of the median prothoracic gland is ex- 
actly like what we have observed in Cerura borealis. It is a trans- 
verse slit situated in the median line of the body, between two 
transverse folds directly behind the head, but yet a little way be- 
hind the front edge of the segment. It has slightly developed lips. 
The points of interest in the partial ontogeny known to us are : 
1. The presence of filamental anal legs exactly homologous with 
those of Cerura, and nearly as long, and the fact that they are much 
longer in the early stages than in the final one ; which seems to 
suggest strongly the view that this genus has directly descended 
from Cerura-like forms ; and that the very long lashes were of more 
use to the ancestors of the present species than to the form we 
now have. It will be remembered that H. marthesia ranges as far 
south as Brazil, and that it may have originated in South America 
and spread northward ; it is also possible that it had a set of ene- 
mies, probably ichneumons, which it has not had to contend with 
in temperate North America, and that the filaments have begun 
to diminish in size from partial disuse. On the other hand, the 
1 American Naturalist, Oct., 1884, 1044. 
