$$ 288, 282. 
THE CRUSTACEA. 
347 
CHAPTER VIII. 
ORGANS OF SECRETION. 
I. Urinary Organs. 
§ 288. 
As yet, Urinary organs have not been observed with the Crustacea 
except in the Myriapoda. 
Here, as with the Insécta, they consist of long, 
small, brownish vessels, caecal, and describing many convolutions about 
the stomach and intestine. 
These Malpighian vessels, as they have been 
termed, open into the digestive canal at the boundary between the stom- 
ach and intestine, and secrete as certainly as do those of the Insecta, uric 
acid, 
With the Chilopoda, there is usually one on each side of the 
pylorus; but with the Chilognatha, there are two, which open, however, 
into the intestinal canal by a common orifice. 
It is now undetermined whether these organs exist also in the other fam- 
ilies of Crustacea. 
But with some Decapoda, there are certain caecal 
vessels which are imperfectly known. 
They open into the intestine at 
various points between the pylorus and rectum, and a more complete 
examination may, perhaps, show them to be ofa urinary nature. 
IT. Organs of Special Secretions. 
§ 289. 
The Astacina have a very remarkable secretion commonly known as 
Crabs-eyes. 
1 For the Malpighian vessels, which were for a 
long time regarded as biliary canals, see further 
under the anatomy of the Insecta. 
2 Ramdohr, Abhandl. tiber d, Verdauungsw. 
&c. p. 149, Taf. XV. fig. 1 (Julus); Treviranus, 
Verm. Schrift. loc. cit. p. 24, 44, Taf. V. fig. 4, Taf. 
VIII. fig. 6 (Lithobius and Julus), and L. Du- 
four, Ann. d. Sc. Nat. loc. cit. p. 86, 96, Pl. V. 
fig. 1, 4 (Lithobius and Scutigera). Scutigera 
differs from the other Chilopoda in having two 
pairs of urinary canals. 
See also Kutorga, loc. cit. p. 6, Tab. I. fig. 2, 
and Miller, Isis, 1829, p. 550, Taf. Il. fig. 5 
(Scolopendra) ; finally Brandt, in Miilier’s Arch, 
loc. cit. p. 322, Taf. XII. fig. 2 (Glomeris). 
8 Swammerdamm (loc. cit. p. 87, Taf. XI. fig. 3) 
had already figured, with Pagurus, a pretty long 
eoecum opening at the posterior extremity of the 
intestine. With Mata squinado, there are three 
such pretty long, of which two are inserted on each 
side of the pylorus, and the third a little further 
pehind (Milne Edwards, Hist. Nat. d. Crust. L. 
p. 76, Pl. IV. fig. 1, m.n.). Lund (Isis, 1829, p. 
1302) has also seen two glandular canals rolled up 
in a knot, which open each side of the pylorus, 
while a third entered the rectum. This last, ac- 
cording to Cuvier (Lecons d’Anat. Comp. ITI. p. 
These are a kind of calculi composed of carbonate of lime 
678) is very common with the Macrura, Brachyura, 
and Anomura, and notably with Astacus fluvia- 
tilis, Homarus marinus, Cancer pagurus, Por- 
tunus puber, and Cancer maenas. But although 
Milne Edwards admits the same also (oc. cit. I. 
p. 76), yet it does not appear to be agreed upon, for 
Meckel (Syst. d. vergleich. Anat. IV. p. 161) cone 
tradicts Cuvier in this respect, and declares that 
he has never found this caecum either with the 
Crabs or with Astacus, Scyllarus, and Palinu- 
rus, but only with Pagurus, Penaeus, and 
Palaemon. Duvernoy, also (Lecgons @’ Anat. 
Comp. V. p. 228), has not observed it in the Ma- 
crura just cited, nor with Galathea squa- 
mifera, and Palaemon serratus, although he 
perceived it with Portunus puber directly behind 
the pylorus, and with Cancer pagurus, near the 
rectum. Like Milne Edwards (Hist. d. Crust. 
I. p. 115, Pl. X. fig. 2, j. (Maia)), I must leave un- 
determined the point whether or not, this glandular 
mass which, with the Decapoda, is concealed under 
the floor of the respiratory cavities in the bottom 
of the cephalothorax, and which opens externally 
by an excretory canal between this same cephalo- 
thorax and the first abdominal segment, —is 
really a urinary organ. 
