§ 307. THE ARACHNOIDAE. 3879 
diverticuli, of the most varied form afd size. Itis continuous into a short, 
small intestine, which passes, in a straight line, to the anus situated usually 
at the posterior extremity of the body. Before reaching this point, the 
intestine has, usually, a dilatation bounded by a constriction, which may be 
regarded as a rectum, or better, perhaps, asa cloaca. With the Tardi- 
grada, the stomach is oblong and occupies a large portion of the body. It 
is divided throughout by numerous constrictions into many irregularly dis- 
posed caeca.” 
With the Acarina, whose anus is placed nearer the middle of the belly, 
there are, nearly always, three short caeca at the anterior part of the 
stomach, and two, longer and more or less constricted, in the lateral regions 
of the abdomen. With some species of parasitic Mites, these appendages of 
the stomach are bifurcated. With the Pycnogonidae, the stomach is short, 
but has five pairs of very long caeca, some of which penetrate into the two 
cheliceres, and others into the eight long legs, even to the extremity of the 
tibiae.” With Galeodes, also, these appendages penetrate the legs, and 
the base of the cheliceres and palpi.” With the Phalangidae, the stomach 
is spacious and has thirty appendages of varied size. Thus, at its upper 
part, there are four rows of short caeca, and, upon the sides, three pairs, 
very long and extending over nearly the whole length of the visceral cavity ; 
the middle pair of these last has, moreover, short sacculi.© With the Araneae, 
the stomach is situated in the cephalothorox, and presents a very remark- 
able disposition. At the posterior extremity of the thoracic cavity, and 
directly behind the sucking apparatus, it is divided into lateral halves 
which extend arcuately in front, and, uniting, form a ring from which are 
given off laterally five pairs of caeca extending towards the points of inser- 
tion of the legs and palpi. 
The intestine arises from this annular stomach, opposite the sucking 
apparatus. It traverses the abdomen on the median line, and terminates, 
before reaching the anus, in a cloacal dilatation. 
2. With the Phrynidae,” and Scorpionidae,® the intestinal canal is 
very simple compared with that just described. It consists of a straight 
1 Doyere, Ibid. p. 324, Pl. XV. 
2 See Lyonet, loc. cit. Pl. XIII. fig. 11, 12; 
Duges, loc. cit. I. Pl. I. fig. 27. 11. Pl. VIL. (Ery- 
thraeus, Dermanyssus and Ixodes) ; also, Tre- 
viranus, Zeitsch. f. Physiol. IV. p. 189, Taf. XVI. 
Ixodes has dichot hic append , of 
which the posterior, at the extremity of the body, 
curve first downwards, then forwards with a long 
course. These various caeca of the Acarina often 
appear, especially when filled with food, clearly de= 
fined, through the skin. But when empty, they 
are frequently overlooked in the small species, 
from the tenuity of their walls. However, I have 
always succeeded, even with the smallest Oribatea, 
in distinguishing the walls of the intestine, especially 
when it contained food. Imust, therefore, consider 
as wholly er! , the opini ly advanced 
by Dujardin (Ann. d. Sc. Nat. ILI. p. 14, or 
Compt. rend. loc. cit. p. 1159), that the food eaten 
by the Acarina does not pass through a distinct 
digestive tube, but is freely effused in the interstices 
of the viscera. 
8 Milne Edwards, Hist. Nat. d. Crust. ITI. p. 
531, and Quatrefages, loc. cit. p. 72, Pl. I. I. 
4 Blanchard, loc. cit. p. 1384. 
6 Ramdohr, Abhandl. ib. d. Verdauungswerk. 
p. 205, Taf. XXIX.; Treviranus, Verm. Schrift. 
I. p. 29, Taf. IIL, and T'ulk, loc. cit. p. 246, Pl. 
Iv. 
6 For the annular stomach of the Araneae, and 
on which, with Tegenaria, Treviranus (Bau d. 
Arach. p. 30, Taf. II. fig. 24, v. b.) has found only 
four caeca, see Brandt, Mediz. Zool. IT. p. 89, Taf. 
XV. fig. 6, or Ann. d. Sc. Nat. XIII. p. 182, Pl. 
IV. fig. 2, or Isis, 1831, p. 1105, Taf. VII. fig. 6 5 
also Owen, Lectures, &c., p. 257, fig. 110; and Was- 
mann, loc. cit. p. 11, fig. 17,18. According to 
this last observer, the four pairs of stomachic caeca, 
with Mygale, bend downwards to the base of the 
eight legs, in order to pass into the thorax where 
they ramify and interanastomose. 
With Argyroneta, and some species of Epeira, 
according to Grube (Muller’s Arch. 1842, p. 208), 
the lateral halves of the stomach are not united in 
a ring at their anterior extremity, but are only con- 
tiguous. 
‘With the Araneae, the walls of the stomach con- 
tain finely-granular cells which, by reflected light, 
have a milky aspect, and secrete perhaps a kind 
of gastric juice. 
7 Van der Hoeven, Tijdschr. &c, IX. p. 68 
(Phrynus). i 
8 Meckel, Beitrage, loc. cit. p. 107, Taf.- VII. 
fig. 13; Treviranus, Bau d. Arach. p. 6, Taf. L: 
fig. 6, and Miller, loc. cit. p. 45, Taf. II. fig. 
