60 INTERNAL ANATOMY OF INSECTS. 



three other cartilaginous pieces, resembling the valves 

 of a bivahe 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 respirafton of the insects concerned. In 

 dissecting a moth related to Catocala Pronuba, 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 ; trachete and bronchia ,- and sacs or 

 pouches c . 



i. Gills (Bronchi^). Having lately described what 



a Reaum. vi. 395. t. xxxvi./. 89. c. c. 



PLATE XXIX. FIG. 21. 



c Marcel de Serres (Mem. du Mus. 1819. 137, &c.) calls the tu- 

 bular trachea that receive the air, arterial trachece, and the vesicular 

 ones which act as reservoirs, pulmonary tracheae. 



PLATE XXIX, FIG. 1.2. 



