PROCEEDINGS OF SOCIETIES. 
15 
tendency to a coecal enlargement backwards, above their junction. The four 
free malpighian vessels (o) are about as long as the ventricle, attenuated and 
doubled back in the middle. The rachidian chord (fig. 5) is composed of a 
larger bilobed cephalic ganglion, an infraoesophagian ganglion, closely joined to 
it, and nine succeeding ganglions of an oval form, the last, as usual, a little en¬ 
larged, the internodes scarcely as long as the ganglions, forming very slender 
threads, which, on closer examination, are found to be double. (Fig. 6.) Some 
other organs were observed in the full-grown larva, which may be the rudiments 
of the reproductive system—viz., a pair of oval vessels, on a long footstalk, and 
crowned by a cone apparently consisting of several filaments pressed together 
(one of these shown, fig. 8) ; and a single but complex organ, composed of an 
oblong hyaline vesicle, terminated by a long filament, and seated on a linear 
footstalk, which sends off* in sucession two long linear branches, the stippled tex¬ 
ture of which announces them to be not mere receptacles, but organs of secre¬ 
tion. (Tig. 9.) Neither the salivary glands nor the silk vessels of the larva 
were discovered. 
The position of the spiracles in the perfect insect having been already speci¬ 
fied, it remains to notice the internal changes from the structure described in 
the larva. The respiratory system is simply tracheal, as before, utricular de¬ 
velopment being regularly restricted to insects that fly. The alimentary canal 
is shortened, the small intestine being absorbed; the ventricle is more ample 
and its chambers better defined; the crop is now oval (c), and behind it the 
membrane presents the appearance of a spiral fold, forming two chambers and 
ending behind with a short csecal protuberance (p). The malpighian vessels 
are now longer in proportion and perfectly linear. Neither in the perfect insect 
nor in the larva did I observe the presence (not to be doubted) of the ordinary 
detergent nuclei of the rectum. Figure 24 shows (at y) two delicate filaments in 
the neighbourhood of the crop. I do not venture to determine whether they are 
connecting threads between it and the salivary outlet, or mere fragments of 
tracheae. Two other capitate vessels (x), shown in juxta-position to the ven¬ 
tricles, are probably only accidentally so seen ; they may possibly be the salivary 
glands cut off and displaced ; as I did not make out that system otherwise. My 
observations on the neurology of the perfect insect are very incomplete, having 
been made on an old dried specimen. The supra and infraoesophagian gang¬ 
lions appeared to have been cut off; in which case the number of ganglions had 
undergone no change in the metamorphosis, as I counted nine remaining, the 
first two of which were somewhat enlarged; the internodes were shortened, and 
the connecting chords much stouter than before, and parted by an evident 
elliptic interval. The ovaries of the female compose each a uniserial spike of six 
long multilocular ovithecae (Fig. 28, d). The only appendage of the oviduct 
observed is shown (at s) as an oval vessel, with granular detached patches of the 
membrane (indicating a function of secretion ?), mounted on a short, slender, 
excretory duct, and ending in a slight filament with a thickened origin. Perhaps 
a more careful examination may discover a triplicate organ, analagous to the 
ordinary structure in Diptera, and foreshadowed by the aforesaid apparatus 
(fig. 9) of the larva. The reproductive system of the male (fig. 26) comprises 
a pair of large, oblong, simple, colourless capsules (gl, with still longer, slender 
deferents (d), a pair of filiform vesicles, hooked 'at the tip (v, and fig. 27), and a 
coecal enlargement of the utricle (g). The forked process shown, embracing 
this last, is probably part of the nervous system. The external grapplers are 
very simple, consisting of a pair of oblong, curved, horny valves, ciliated along 
the under edge and around the tip (fig. 25). 
Now, to recapitulate the points of agreement and difference between this 
group and the orders to which it has been annexed or approximated; we find 
the metamorphosis totally unlike that of Hemiptera, from which also, in particu¬ 
lar, the Pulicidae differ in the not unimportant point of the pentamerous develop¬ 
ment of the tarsi; and the whole structure of the mouth, except so far as the 
lancet-like shape of some of the organs is in both alike subsidiary to the fluid 
aliment, or so far as the articulated sheath in Hemiptera may be considered to 
represent the palpi coalesced. The relation to the Coleoptera, suggested by 
