INTERNAL ANATOMY GF INSECTS. 69 
resemble the seed-vessels of some species of Thlaspi, 
while others appear to form a file of oblong ones?*. 
Near each of their spiracles also is a vesicle which ap- 
pears to be a reservoir>. 
But this kind of structure is not confined to insects 
strictly aquatic. Even such species of terrestrial ones as 
live upon aquatic plants, and are, consequently, necessa- 
rily or accidentally often a considerable time under wa- 
ter, are furnished with some apparatus by means of 
which they can exist in this element for a considerable 
period. For example, most of the Weevils (Cureulio L.) 
die in a short time if immersed in water; yet the species 
of the genera Tanysphyrus Germ. Bagous Germ., and 
that to which C. pericarpius L. belongs, and which feed 
on aquatic plants, can exist for days under water, as I 
have ascertained by experiment. C. lewcogaster Marsh, 
and another of the same tribe, swims like a Hydrophilus, 
and will live a long time in a bottle filled with water and 
corked tight. Other insects also, that are not at all aquatic, 
have pneumatic pouches. A striated or channeled ve- 
sicle I have found under the lateral angles of the collar 
in the humble-bee, where Chabrier supposes the vocal 
spiracles are situate ; and also at the mouth of the spira- 
cles of the metathorax in Vespa, &c.© In Sphinx Li- 
gustri the bronchie terminate in oblong vesiculoso-cel- 
lular bodies, almost like lungs*; in Smerinthus Tilie 
these are preceded by a simple vesicle bound with spiral 
‘fibres®. M. Chabrier thinks that these air-bladders of 
@ Prate XXIX. Fic. 9. a, 6. Reaum. vi. 418—. 450. 
> Cuv. Anat. Comp. iv. 441. © Vor. II. p. 585. 
4 Sprengel Comment. 17. t. iii. f. 24. © ibidst aol 1. 
