$ 280. THE CRUSTACEA. 333 
Daphnia, and Apus, alone, the anterior extremity of the intestinal canal 
has several single or ramose caeca, the walls of which appear to serve prin- 
cipally as hepatic organs. With the Cirripedia, similar caeca exist on the 
stomach, and form, evidently, the transition to the hepatic organs of the 
other Crustacea,— that is, to an isolated.liver with special. though short excre- 
tory canals. Such an isolated liver occurs with the Laemodipoda, Iso- 
poda, and Amphipoda, and contists of long varicose caeca arising from the 
base of the stomach, and accompanying the intestine a considerable dis- 
tance.” 
With the Poecilopoda, Stomapoda, and Bopyrina, the hepatic organy are 
inserted at various points along the digestive canal.® Finally, with the 
Decapoda, the liver consists of two glandular masses composed of mure or 
less ramose caeca loosely bound together. Each of these glands, which 
sometimes occupies only the sides of the cephalothorax, but sometimes, also, 
largest portion of the alimentary canal dotted with 
small, yellowish-brown follicles, which I can only 
regard as hepatic organs, although other Zooto- 
mists consider them as Malpighian canals (see 
287). L. Dufour (loc. cit. p. 96, Pl. V. fig. 4, 
.) has found these follicles in the stomach of Scu- 
tigera, but did not regard them as hepatic. 
The numerous large cells, which, according to 
Serres (Ann. du Mus. d’Hist. Nat. XX. p. 250), 
cover the external tunic of the intestine of Litho- 
bius, are certainly only follicles of this kind.* 
5 With Daphnia, there are two lateral, back- . 
wardly-curved caeca, which ascend from the ante- 
rior extremity of the digestive canal towards the 
dorsal surface of the head ; see Schaffer, loc. cit. 
Be 41, Tat. IL. fig. 2, k. k.; Straus, loc. cit. p. 
O1, Pl. XXLX. fig. 6, 8.0. s., and Jurine, Hist. d. 
Monocl. Pl. IX. X. fig. 7, XI-XIII. 
Branchipus, and Artemia (Joly, loc. cit.), the 
anterior extremity of the digestive tube has also 
“two short caeca which, with the glandular tunic 
with which the remainder of the intestine is cover- 
ed, should be regarded as a liver. With Argulus, 
the stomach his two multiramose caeca, which lie 
in the parenchyma of the body (Jurine, loc. cit. p. 
441, Pl. XXVI. fig. 1-3, 9, or Vogt, loc. cit. p. 8, 
fig. 1,9). With Apus, these caeca are given off 
from the anterior extremity of the digestive canal 
and do not extend beyond the anterior border of the 
cephalothorax (Schaffer, loc. cit. p. 70, Taf. V. 
fig. 15, a.a.). According to Zaddach (loc. cit. p. 
8, Tub. I. fig. 10-13, and Tab. IV.), these caeca 
contain numerous glandular follicles.f 
6 Beside the figures of these stomachic append- 
ages in the works of Cuvier, Burmeister, anc 
Martin St. Ange, see also particularly those which 
Karsten (Nov. Act. Nat. Cur. XXI. p. 301, Tab. 
XX. fig. 1-4) has given of the hepatic organs sur- 
rounding the pylorus with Badanus. 
7 With Cyamus, there are two long hepatic 
canals which wiud over the digestive canal (Rous- 
sel de Vauzeme, loc. cit. p. 252, Pl. IX. fig. 19). 
The two stomachic appendages of [dothea which 
Rathké (loc. cit. p. 121) has taken for adipose 
bodies, belong to the hepatic apparatus which here, 
according to my observations (Miidler’s Arch. 
* [ § 280, note 4.] For the liver of Julus, see 
Leidy, loc. cit. He says, “At the termination 
of the proventriculus, there open two biliary tubes, 
and from it, surrounding the commencement of the 
ventriculus, is suspended a broad, white, opaque, 
reticulated band, apparently composed like the 
rete adiposa of insects.” — Ep. 
t [ § 280, note 5.] The hepatic nature of these 
appendages with Artemia and Argulus is denied 
With” 
1837, p. 435) consists of three pairs of yellow vari- 
cose tubes. With Oniscus, Porcellio, Asellus, 
and Lygidium, there are four very long varicose 
hepatic tubes which open right and left into the 
pylorus (Treviranus, Verm. Schrift. I. p. 57, Taf. 
VIL fig. 38, Taf. IX. fig. 50, Taf. XI. fig. 64; 
Brandt, Mediz. Zool. II. p. 75, Taf. XV. fig. 395 
Lereboudllet, loc. cit. p. 180, Pl. V. fig. 25; Kars- 
ten, ioc. cit. p. 296, Tab. XXVII. fig. 1). Tre- 
viranus, who did not observe the excretory ducts 
of these glands regarded them as masses of fat, 
while Ramdohr (Abhandl. tib. d. Verdauungsw. 
&c. p. 204, Taf. XXVIII. fig. 5), who, probably by 
mistake, has figured with Porcellio three similar 
appendages, has taken them for salivary organs. 
There are three pairs of hepatic canals with Cymo- 
thoa (Meckel, Syst. d. vergleich. Anat. IV. p. 154), 
Aega (Rathké, Nov. Act. Nat. Cur. XX. p. 30, 
Tab. VI. fig. 16, d. d. 18), and Lygia (Milne Ed- 
wards, Tist. Nat. d. Crust. Pl. IV. fig. 3). I can- 
not now decide whether Hied/a has really only one 
varicose hepatic tube, or whether the others were 
overlooked by Straus (loc. cit. p. 59, Pl. IV. fig. 
15). With Gammarus, and the other Amphipoda, 
I have found two pairs of long hepatic tubes. 
Frey and Leuckart (Beitr. p. 104) have found 
with Caprella, as with Cyamus, two simple hepa~ 
tic coeca. A 
8 With Limulus, there are four groups of inter- 
laced caecal canals situated in both sides of the 
cephalothorax. The bile is poured into the ante- 
rior portion of the intestine by four distinct excre- 
tory ducts, which are widely separated from each 
other (Van der Hoeven, loc. cit. p.18, Pl. II. fig. 
1, 5,8). With Squilda, Bopyrus, and Phrycus, 
the digestive canal has ramose or varicose hepatie 
caeca on both sides, at irregular intervals, of its 
whole length (Miller, De Gland. Struct. p. 70, 
Tab IX. ; Duvernoy, Ann. d. Sc. Nat. VI. 1836, 
p. 243, Pl. XY. fig. 1 (Squi/la); and Rathké, De 
Bopyro et Nereide, p. 9, Tab. I. fig. 7, and Nov. 
Act. Nat. Cur. XX. p. 47, (Bopyrus and Phryax- 
us.) The genus Mysis (Frey, loc. cit. p. 19) on 
the contrary, which has eight hepatic canals open- 
ing right and left into the base of the stomach, re- 
sembles again the Amphipoda and Isopoda. 
by Leydig (Ueber Argulus, &c., and Ueber Ar- 
temia, &c , loc. cit. Siebodd and K élliker’s Zeitsch. 
II. p. 334, and IIL. p. 286) on histological grounds 5 
it is most probable however that they serve as a 
liver, since Will (Muller’s Arch. 1848, p. 506) has 
shown, by chemical analysis, the hepatic nature of 
analogous caecal tubes with Daphnia and Cyclops. 
— Ep. 
