Such correspondence has not been observed in any other 
Lepidopterous insect. 
If we take into account the fact that Zonosoma (Ephyra) is a 
characteristic Geometrid genus, although its method of pupal 
suspension is unique in a family whose species make cocoons 
or bury, we may feel confident that it has been descended from 
cocoon-making ancestors, and that Hugonia quercinaria and 
Uropteryx sambucaria give us a clear idea of the steps by 
which the reduction was effected. 
The effect of Gravity upon the shape of suspended pupx such 
as those of the Nymphaline.—Kvery naturalist who has 
watched the pupation of a Vanessid must have observed 
the extraordinary mobility of the abdominal region of the 
freshly-expored chrysalis. Movements of remarkable ampli- 
tude take place in every direction, and especially in the 
dorso-ventral plane, these latter being essential for the with- 
drawal of the posterior segments from the larval skin and 
the remarkable feat of attachment to the silken boss close to 
the point from which the skin itself is hanging. Success is 
only rendered possible by the remarkable contractile power 
of the intersegmental muscles along the median ventral area. 
These, by their contraction, keep the rigid hook-armed apex 
of the abdomen firmly pressed to the outside of the larval 
skin up which it is being forced, and enable it to press down 
or push aside any of the stiff spines which oppose the move- 
ment: these finally bring it to the small silken boss which 
alone provides a secure basis of attachment for the terminal 
hooks. For this purpose the ventral muscles require to be 
far stronger than those of any other region, and we invariably 
find that they entirely overbalance the dorsal intersegmental 
muscles in pup which have been produced on the floor of 
the breeding-cage. In such pupe the abdominal segments 
are curved round towards the ventral side, so that the long 
axis of the apical part forms at least a right angle with that 
of the thoracic region, and this attitude becomes stereotyped 
with the hardening of the pupal cuticle and the consequent 
loss of all power of dorso-ventral movement. These free 
pup forra a striking contrast with the normal attached 
individuals in which the long axis of the abdominal segments 
