Notes in 1887 upon lepidopterous larve, de. 575 
means of the claspers. The young larve of all species 
which exhibit this attitude habitually rest on the midrib, 
or one of the chief lateral veins on the under sides of 
leaves, and therefore with the dorsal surface downwards. 
When older the larve rest upon twigs, with either a 
vertical or a horizontal direction: in the former case 
the posterior extremity is lowest, in the latter the dorsal 
surface may be either above or below, according as the 
larva clings to the upper or under side of the twig. 
When the larva rests on the upper side in a horizontal 
position, the Sphinx attitude is never strongly marked. 
Hence it is clear that in all the younger stages, and 
for a large part of the last stage, such larve are subject 
to strains which tend to bend the anterior part of the 
body downwards. Under these circumstances the 
organism reacts upon the strain, and the muscular 
body-walls strongly contract upon their fluid contents in 
such a manner as to produce compensating rigidity, and 
giving to the body the curve which is characteristic of 
the attitude. The Sphinx attitude is to be explained as 
the combined effect of gravity and of muscular reaction 
upon the anterior unsupported parts of the body. The 
muscular arrangements which are most favourable for 
counteracting these strains are also made use of in the 
older larve for the maintenance of a feebly-marked 
Sphinx attitude, when the larva is seated on the upper 
side of a horizontal twig. The attitude is most strongly 
marked when the larva is resting on a vertical twig, 
because gravity tends to draw the anterior part of the 
body backwards as well as downwards. These large 
larve habitually rest on vertical twigs with the head 
uppermost, because the twig itself is approached from 
its base, and gradually stripped of leaves towards its 
apex. The essential dependence of the attitude upon 
eravity is well seen when a vertical twig, with a larva 
upon it, is carefully bent downwards so that the strain 
is in the opposite direction, and tends to bend the 
anterior part forwards instead of backwards: under 
these circumstances the larva begins to yield to the 
strain in a few minutes. When the larve of Smerinthus 
ocellatus are kept in large numbers, it is common for 
many of them to suffer from a disease of which the first 
symptom is a partial failure in the tonic contraction of 
the body-walls. The anterior part of the body, there- 
