260 
MEMOIRS OF THE JS^ATIOXAL ACADEMY OF SCIENCES. 
Stage 1 F.— Leuj^tli of body, 12 inm., and of tails, G inin.; total, 18 mni. Head yellowish green, 
narrowing’ toward the vertex, flattened in front, with two broad pink lateral bands, which meet 
above, and are broadly bordered behind with pale straw-yellow. Body ])ale, distinct green, 
speckled in parallel lines with reddish brown, thei'e being ten oblique, ])ara]lel, pale yellowish, 
lateral stripes passing downward and backward, the first one on the second thoracic segment 
very short, being one-third as long as the next one. Two liigh, slender, conical, pinkish red 
tubercles on the prothoracic segment. A dorsal broad yellow band, becoming pinkish on the 
suranal plate; the line is broken into a series of smooth yellow swellings, four or five on a 
segment. The tails are greenish, with a slender internal pink thread line, the ends with the 
flagella (or eversible portions of the stemapods) deep coral-red. 
(In some alcoholic specimens in the United States National ]Museum the length of body, not 
including the tails, is 22 mm.; of the tails, 8 to 9 mm.; length just before molting, 28 mm,; of the 
tails, 10 mui.; total, 38 mm. The larva is much as in the third stage; the prothoracic tubercles 
as before, but slightly smaller iu proportion to the body. The tails are as in Stage III, the flagella 
Jiearl}^ as long as the sheath, which is red at the end.) 
Stage V and last — Length of body, 40-42 mm. ; of tails, 4-5 mm. ; total, 44-47 mm. 
It will now be seen that the tails are only about oiie-teuth as long as the body, while in Stages 
I and II they are about two-thirds as long as the body. 
It is a large-bodied, pale green cateri)ilhir, thickest iu the middle, being somewhat spindle- 
shaped. The head is moderately large, flat in front, subcouical, with the vertex high and conical, 
l)ale green, edged very irregularly with roseate on the sides. A small, double reddish tubercle on 
the top of the prothoracic segment, from which a median white or yellow dorsal stripe, here and 
there marked with roseate spots, passes back to the suranal plate. The anal legs are represented 
by two slender filaments held outstretched, which are nearly as long as the body is thick. There 
are seven pairs of oblique, latei’al, faint yellowish, slender stripes, the last i)air extending to the 
.«ides of tlie anal filaments. All the legs are pale green and coucolorous with the body. 
A great change has occurred in the prothoracic tubercles which are now two low, flattened, 
incons])icuous warts on the upturned or flaring edge of the segment. The anal legs are much 
■shorter in i>roportiou and not so long as the body is thick, being about one-third as long in proportion 
ns 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 iu this respect like that of Cerura, so carefully Avorked out by 
Prof. E. B. Poulton. The opening is hard to find. The opening of the median luothoracic gland 
is exactly like Avhat Ave have observed in Cerura borealis. It is a transverse slit situated in the 
median line of the body, between two transverse folds directly behind the head, but yet a little 
Avay behind the front edge of the segment. It has slightly deA^eloi)ed lips. 
The points of interest in the ontogeny known to us are as follows: 
The congenital characters are the enormously long stemapoda, in proportion to the body, and 
the pair of long, prominent prothoracic tubercles. 
The acquired characters are the dorsal line, the oblique yellow bars, and the gradual reduction 
iu the length of the tail. 
Other features 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 is the ancestor of Cerura, and that the very 
long lashes Avero of more use to the ancestors of the present species than to the form Ave now 
have. It will be remembered that M. martliesia ranges as far south as Brazil, and that it may have 
originated in South America and spread northAvard ; it is also possible that it had a set of enemies, 
probably ichneumons, which it has not had to contend Avith in temperate North America, and 
that the filaments have begun to diminish iu size from partial disuse. On the other hand, the 
spraying apparatus lodged in the first segment next to the head seems to i)erform its function 
in uudiminished vigor. Experiments like those made by Mr. Poulton on the fluid secreted by 
Cerura should be conducted Avith the present insect, 
(2) The second point is the comiflete reduction in size of the two high prothoracic spine-like 
■ tubercles which takes place at the last exuviation. 
