of the Oil Beetle, Meloé, and of the Strepsiptera. 345 
it. The mass was brought into view precisely in the middle line, between the 
caudal sete, at the instant when the larva was in the act of carrying its poste- 
rior segments forward, so that the fact could hardly be mistaken. This appears 
to be sufficient evidence of the existence of an anal outlet to the digestive 
canal. That this may become closed at a subsequent period, when the Sty- 
lops larva has, penetrated into the interior of the body of its victim, is highly 
probable, although it is most certainly permeable in the male imago, which 
Mr. Pickering saw void a whitish fluid immediately after it came forth, analo- 
gous probably to that passed at a similar period after evolution from the pupa 
state by the Lepidoptera and other insects. The Stylops larva, near the end of 
its period of nutrition, in its apodal state, has been found by Peck, Jurine and 
Dufour completely inclosed in the body of the hymenopterous insect, feeding, 
according to Dufour's observations, on the adipose tissue only, and not on the 
vital structures. : 
Respiratory Oreans or STyLops. 
The complete occlusion of Stydops within the body of another insect ren- 
ders the consideration of the manner in which the function of respiration is 
performed, or the aération of the fluids in the parasite is effected, —a condition 
essential to lifej,—a matter of interest equal with that of the closure of the 
outlet to the digestive canal. It can hardly be imagined that an insect, the 
male sex of which in its perfect state is one of the most active and fully deve- 
loped of the winged tribes, does not possess, in its larva state, organs in some 
form or other fitted for an extensive aération of its fluids. The existence of 
a large spiracle in the thorax of the female Stylops communicating with large 
tracheze extensively ramifying through its tissues, shows that while it is pass- 
ing the greater portion of its existence surrounded by delicate organs in the 
body of another animal, and as it were bathed in its fluids, it yet maintains 
for itself a free and perfeetly independent respiratory function of its own. 
In all the larvze I have examined there have appeared to be eight pairs of 
bag-shaped dark-looking bodies within the abdomen, one pair at the sides of 
encli agant, ipe the fifth, or second abdominal segment to the eieventh 
Wenham appt nad rec attori e 
? r resemblance to branchial 
sacs, these may perhaps be regarded, at this period of the larva's existence, as 
