= ere 
SIGE. 271 
as to be at least 0.5 mm. in diameter ; 
on the first segment it broadens slightly, 
and in front of the expansion commences 
to diminish gradually and slightly in 
size, so that when it enters the thorax 
(from the abdomen) it becomes reduced 
to a diameter of only 0.20—0.25 mm. 
As soon as it enters the thorax it be- 
gins to plunge downward, until the 
constriction of the metathorax is passed, 
or during a course of about 38 mm. It 
then increases gradually in size again 
to about 0.45 mm., but instead of run- 
ing directly to the head it passes in an 
oblique Girection upward between the 
muscles of each side of the body, and 
when it has nearly traversed the thorax 
doubles upon its course, passing beneath 
the portion already mentioned, and then 
turns back again beneath its former 
course toward the head; the trebled 
portion extends over an area fully 5 mm. 
long, and no such marked mesothoracic 
enlargement as oceurs in the imago was 
noticed ; when it enters the head it has 
become reduced to a slender thread about 
as large as the oesophagus. The whole 
dorsal vessel from the head to the fourth 
abdominal segment (behind which it 
becomes much reduced and obscure) is 
30 mm. long, when extended. 
Nervous system. In the 7-days’ . 
chrysalis a great nervous mass is seen 
a little in advance of the middle of the 
thorax, a little larger than that of 
Hamadryus; the lateral nerves from it 
appear to be double at their origin, and 
to be inclined forward ; behind this gan- 
glion the cord is very slender, and at a 
distance of 4.5 mm. from the extremity 
of the ganglion emits a pair of slender 
but very distinct nerves, which are 
directed backward but divaricate con- 
siderably ; there is no ganglionic en- 
largement at their origin. At a distance 
of a millimetre and a half behind this, 
where the cord enters the abdomen, it 
becomes and thereafter continues stouter, 
being enclosed in a nebulous wrapping, 
described by Dufour in the abdomen of 
the imago of other lepidoptera as a 
fibro-muscular, white membrane. At a 
further distance of 2.75 mm. we come 
to an exceedingly slight ganglioniform 
swelling, having no lateral nerves spring- 
ing from it; probably this is what 
Dufour refers to as a white, fibrous, 
ellipsoidal capsule embracing the cord 
at this point. The last two ganglia are 
1.25 mm. apart, measuring from their 
posterior extremities. 
In front of the thoracic ganglion the 
cord is stout, 0.15 mm. in diameter ; 
from the ganglion to where it divides 
around the oesophagus is 1.5 mm., and 
the forks are about 0.5 mm. long. 
In a 9-days’ chrysalis the cord has not 
yet attained its complete development, 
as is readily seen by its sinuous course 
between the thoracic enlargement and 
the lateral nerves, which diverge from 
the cord before the abdomen is reached, 
where, in a distance of 3.5 mm., the 
cord is 4.5 mm. long, making three 
sinuous curves in reaching this point; 
these nerves pass not to the legs but to 
the inflated longitudinal branchial can- 
als ; they originate 1.7 mm. in advance 
of the abdominal line, and 2.8 mm. 
behind the thoracic mass. 
The nervous cord apparently enlarges 
as it reaches the abdomen, being envel- 
oped in a thin film in which the lateral 
nervesrun. The first abdominal ganglion 
