Dr, T. A. Chapman on Heterogyna penella. 145 
and lower jaws of one of these reptiles whose gape is 180°. 
Their edges are smoothly continuous by the stretching of 
the material at their angle of union in the last thoracic 
segment, so that there is in fact no such angle or any 
danger of the slit continuing further down the pupa, the 
upper and lower sections being continuous, without any 
appearance of being separated by an open fissure or 
crack. 
The moth when emerged retains an organic connexion 
with the pupa-case, and this is its most unusual feature. 
The imaginal legs, or rather the positions they should 
occupy, remain inseparable from the minute black papillee 
that represent them in the pupa. If any attempt be 
made to separate the imago from the pupa case at this 
point, the pupal legs break away from the rest of the case, 
or more frequently, the separation is made at the expense 
of the imago, leaving bleeding wounds. The ‘imaginal 
head continues also to occupy the pupal head; only twice 
have I seen it separated naturally, but it is not very 
difficult to extricate the head of the imago from that of 
the pupa. The imaginal head is almost identical with the 
pupal head, except that it is white and colourless and 
- obviously not intended to be exposed, the antennz and 
mouth parts existing as structureless elevations. 
This, however, is not the only means by which the 
moth maintains its position. Organically connected with 
the anterior flap of the pupa case, the moth lies across the 
open mouth of the pupa, and its hinder extremity lies 
along the dorsal flap, formed of the dorsal thoracic seg- 
ments. The ventral surface of the moth is swollen, so as 
exactly to fit the hollow these form in their inner surface, 
and there it adheres either by the suction of atmospheric 
pressure, or by an actual stickiness of the apposed surfaces. 
The bulb of the posterior segments of the pupa being still 
within the cocoon, the moth appears to be sitting across 
the mouth of the cocoon, the pupa case not being visible 
on a casual glance, though the moth is in contact with it 
throughout its whole ventral surface, except just centrally 
opposite the lumen of the chrysalis case. Fertilisation 
occupies five or ten minutes only, and this may be the 
whole duration of the imaginal existence outside its pupa 
case, since, as soon as this is accomplished, the moth com- 
mences to return into it and completes the process in 
about an equal time. Strong vermicular movements 
