60 INTERNAL ANATOMY OF INSECTS. 
three other cartilaginous pieces, resembling the valves 
of a bivalve shell, close the passage within the pointed 
pieces 3 . At this orifice the water is received; and 
when, by an internal process to be described afterwards, 
it has parted with its oxygen, is again expelled. 
Under this head I shall mention a fact which may be 
connected with respiration of the insects concerned. In 
dissecting a moth related to Catocala Promiba, but I 
do not recollect the particular species, — at the base of 
the abdomen of the male I discovered two bunches of 
long fawn-coloured parallel hairs, planted each in an 
oval plate, plane above, but below convex and fleshy ; 
while the plates remained attached to the insect, they 
appeared to have a distinct pulsation. The hairs, which 
are about half an inch long, diverge a little, and form a 
tuft not very unlike a shaving-brush b . I have not since 
met with this species, but I have preserved the brush 
and scale. Somewhere in Bonnet's works, but I do not 
recollect where, I have since found mention of a similar 
fact in another moth. 
II. Having considered the external respiratory organs 
of insects, by which the air is received, we are next to 
consider the internal ones, by which it is distributed. 
These are gills : trachea and bronchia ,• and sacs or 
pouches c . 
i. Gills (Branchice d ). Having lately described what 
a Reaum. vi. 395. t. xxxvi./. 8—9. c. c. 
«> Plate XXIX. Fig. 21. 
c Marcel de Serres {Mem. du Mus. 1819. 137, &t.) calls the tu- 
bular trachcte that receive the air, arterial trachea-, and the vesicular 
ones which act as reservoirs, pulmonary tracheae. 
d Plate XXIX. Fia. 1.2. 
