210 
Mr. W. Sells’s Notes, fy c. 
neath the hinge, and the other about three quarters of an inch 
lower down. At the moment, I conceived this to be the first dis- 
covery of the fact, but have since been informed that it has been 
spoken of by Mr. Kirby, although I have not succeeded in finding 
his notice of it. Now it is highly improbable that so complex an 
additional apparatus should be without its appropriate use ; and 
yet, one nest has not the least vestige of it; therefore, in that 
case, it may be confidently presumed that it was not required. 
In order to explain this diversity of structure, the following sug- 
gestions have occurred to me as a plausible mode of accounting 
for it. In newly constructed nests the reacting elastic pow r er of 
the hinge may be all-sufficient, and continue so for a considerable 
time ; but from long continued use, the effect of weather, or other 
incidental causes, it may lose its spring, when the superadded con- 
struction of the valves may effectually restore its efficiency ; as it 
is evident, upon close inspection, that the opening of the lid acts 
first upon the upper one, the decussating fibres of the crura of the 
upper valve act upon the lower one, which again sends out nume- 
rous elastic threads downwards. If this explanation be correct, 
it is calculated to double our admiration of this creature’s work- 
manship, proving as it does that the great Architect of all has 
gifted this interesting insect with such a measure of accommo- 
dating instinct. 
PLATE XIX. 
Fig. 1. View of the interior of the upper part of the nest; a, the lid raised and 
kept back by a needle. 
2. View of the interior of a section of the lower end of the nest; a, shows 
the cut surface of the thickened portion. 
3. Upper surface of the lid ; a a, angles of the binge. 
4. Section showing the internal structure ; a, under-surface of the lid ; b b, 
the cut surfaces of the upper portion of the nest, showing its great thick- 
ness and strength ; c, the upper valve and the lower valve. 
5. A perfect nest as preserved by injecting it with wax. 
6. Specimen of Cteniia nidulans. 
7. Internal view of the left mandible. 
8. External view of the right mandible. 
9. Magnified view of the eyes and the tuft of strong bristly hairs in front of 
the thorax. 
