428 THE INSECTA. § 3839. 
plan. It exceeds more ‘or less the length of the body, and there is a crop 
at the posterior extremity of the cesophagus upon which succeeds a long 
and tortuous stomach. Upon the cardiac portion of this last there are 
inserted two to four cacca directed either forwards or backwards, and with 
some larvae of the Muscidae, there is also a long, sucking stomach upon 
one of the sides of the cesophagus.®” 
With the larvae of the Neuroptera, which suck up their liquid food through 
tubular mandibles, the posterior extremity of the esophagus is dilated into 
a pyriform sucking stomach, which is followed by the proper stomach, 
large, of median length, and slightly flexuous. The extremely small ileum 
is long and makes several convolutions, while the colon is large, vesiculi- 
form, and continuous into a horny tubular rectum. 
§ 839. 
As to the grandular appendages of the digestive canal of the Insecta, 
the Salivary Organs are quite widely distributed, as well with the Imagines 
as with the Larvae and feeding Pupae. These organs consist of one, or 
two, rarely three pairs of colorless tubes of unequal length. These are 
sometimes prolonged into the thorax, while in other cases they accompany 
the digestive canal into the abdominal cavity where it makes many convo- 
lutions. Their excretory ducts are composed of a solid membrane, and are 
distinctly separated from the glandular portion.” This last is composed 
of three layers, namely: an external, homogeneous envelope, — an intimate 
tunic accompanying the excretory duct, — and a middle layer composed of 
colorless, glandular, nucleated cells, which often form very fine excretory 
tubes opening into the common duct. Frequently, also, these ducts contain 
a spiral filament like the tracheae; they open, each, at the base of the oral 
cavity by a distinct orifice, and it is rare® that they unite, forming a 
common duct; sometimes they have, near their excretory openings, special 
salivary reservoirs.© | With very many Aptera,® Diptera, Lepidoptera, 
and Coleoptera, the salivary organs consist of two simple tubes, which, 
with the larvae of the second and third of these orders, often extend a con- 
siderable way into the abdominal cavity.” With the Cerambycidae, Te- 
87 See Swammerdamm, Bib. der Nat. Taf. XLI. 
fig. 6, Tab. XLIII. fig. 5 (Stratiomys and Pio- 
phila); Ramdohr, loc. cit. Taf. XIX. fig. 1 
(Musca) ; L. Dufour, Ann. d. 8c. Nat. XI. 1839, 
1 For the intimate structure of these organs, see 
Af. Meckel, in Muller's Arch. 1846, p. 25, Taf. I. 
IL. 
2 Piophila, Musca, Sarcophaga, Tabanus, 
p. 212, Pl. V. fig. 28, XIL. p. 13, 18, Pl. I. fig. 1, 
4, and I. 1844, p. 372, Pl. XVI. fig. 8 (Ceroplatus, 
Sapromyza, Piophila). 
The metamorphosis of this digestive canal, in 
the pupa of Sarcophaga carnaria, is represented 
in a suite of figures published by Suckow, in 
Heusinger’s Zeitsch. III. Taf. IX. fig. 147-163. 
But Suckow has fallen into the same error as 
Ramdohr (loc. cit. p. 171) in regarding the caecal 
append of the stomach of the larvae as- four 
tubes connecting the stomach with the saliyary 
canals. 
“$8 See Ramdohr, loc. cit. p. 154, Taf. XVII. fig. 
3 and L. Dufour, Recherch: &c. p. 589, Pl. XII. 
ig. 175 (Myrmeleon). The large intestine together 
with the rectum, does not serve, with this larva, ag 
dees organ, but, as is very extraordinary, 
the function of a Spinneret (see § 347). 
Hippobosca, Oestrus, Mordella, Mantis, and 
Forficula. 
3 With Forficula, Musca, Sarcophaga, and 
Hippobosca, each of these excretory ducts is dilated 
into a roundish reservoir ; but with the Termitidae, 
Acrididae, Achetidae, and Mantidae, there is an 
oblong, pedunculated reservoir common to both 
ducts. See, for the figures, the various memoirs of 
L. Dufour. 
4 With the Nirmidae. 
5 Pyrochroa, Livus, Phyllobius, Diaperis, 
Lema, Oedemera, Chrysomela, Coccinella. In 
this last genus, the two salivary vessels are to- 
Tose, 
6 See the figures in the works nf Swammerdamm, 
Lyonet, Ramdohr, Suckow, Herold, and L. Du~ 
four, 
