274 PSY CHS. 
3-4, 1.25 mm.; 4-5, 0.5 mm.; 5-6, 1.5 
mm. ; 8-9, 2 mm. 
Silk vessels. They agree in appear- 
ance with those of Hamadryas and reach 
the middle of the sixth abdominal seg- 
ment, where they are attached. 
Male generative organs. ‘Testes pink- 
ish red, the median line much deepest 
in color, longitudinally oval, nearly four 
times as long as broad, filled with a whit- 
ish granular matter, and situated in the 
middle of the fifth abdominal segment. 
4, THE LARVA OF AGLAIS URTICAE, OF EUROPE. 
Observations on the changes in the 
nervous system of this species, in pass- 
ing from the larval to the pupal state 
and during the continuance of the latter, 
as also some statements regarding the 
structure of the tracheae, will be found 
in Newport’s papers. See also other 
papers referred to in the introduction. 
Digestive system. The under branch 
of the malpighian vessels passes along 
the under outer surface of the stomach 
as far as the hinder part of the second 
abdominal segment; the branch which 
extends along the upper outer wall of 
the stomach appears to extend as far 
only as the middle of the fourth abdom- 
inal segment. 
Nervous system. The last two ab- 
dominal ganglia are so closely united 
as to conceal their point of union, as in 
Euphoeades troilus; and in other re- 
spects they closely resemble that species. 
Glandular system. The silk-vessels 
are of uniform size throughout, and they 
therefore do not present that distinction 
into two parts, a vessel and a couduct- 
ing tube, which holds in Danais. 
Male generative organs. The anterior 
thread of the testis is fully half as long 
as the testis itself, measuring one milli- 
metre in length, while in Hamadryas no 
thread was found. 
5. THE PUPA OF AGLAIS URTICAE, OF EUROPE. 
Muscular system. The mesothorax is 
almost entirely given up to muscular 
bundles, the principal portion of which, 
for the movement of the future wings, 
is divisible into two sets. One of these 
sets is restricted to the lower part of 
the sides of the thorax, and its fibres 
are directed from the base of the wings 
toward the middle of the lower surface, 
those of the opposite sides inclining 
toward each other at a little more than 
aright angle. In the V-shaped space 
between them, and including all the 
upper domed part of the mesothorax, 
is the other set, running longitudinally 
in five superimposed layers. 
Digestive system. The tortuous in- 
testine is 9.5 mm. long. 
Male generative organs. ‘The testis 
is extensively clasped by the tracheal 
vessels of the fifth abdominal segment. 
It looks as if made up of layers of fibrous 
material, more distinguishable because al- 
ternately darker and lighter ; the anterior 
thread is one millimetre long, or fully 
halfas long as the diameter of the testis. 
The testis is perfectly crammed with 
spermatozoa. These appear to be 
