560 CLASS IX. 
of the intestinal canal there are in addition four small blind appen- 
dages on each side!. In the spiders (Aranea L.) the cesophagus is 
narrow, horny, bent first downwards, then upwards, and terminates 
in a part which proceeds backwards, and can be dilated by muscles 
attached to it?.. This part becomes at its extremity more membra- 
nous, and passes into the intestinal canal, which sends two lateral 
arms forwards that bend themselves round in the cephalothorax 
and approach each other or unite so as to form an annular stomach. 
From this ring blind eversions proceed towards the feet, bend 
downwards, and communicate with each other. From the same 
point where the two lateral arms arise a middle canal exists, which 
runs towards the abdomen and is gradually dilated in some degree. 
The widened part receives on each side two large canals which 
branch through the adipose body ; the intestinal canal then narrower 
curves upwards and afterwards proceeds downwards, where, pre- 
vious to its termination, an oval ccecum is situated laterally. 
Organs of different form for the secretion of saliva are observed. 
in most genera of this class, and probably are wanting in none of 
the arachnids, although their opening into the intestinal canal has 
not been detected in all. In the Scorpions, where Mecxe® de- 
nied altogether the existence of salivary organs, two longitudinal 
sacs placed in the fore part of the abdominal cavity, their tortuous 
canals running forwards in the cephalothorax, probably serve for 
the secretion of saliva’. From the secretion of saliva the poison 
should be distinguished, with which different species kill their prey 
previous to devouring it. In the spiders there is situated at the 
base of each of the mandibles, or sometimes in the mandibles them- 
selves, a vesicle, surrounded by a layer of flat spirally turned fila- 
ments, from the anterior part of which a narrow duct arises, that 
runs towards the point of the upper jaw. ‘This poison has an effect 
1 RAMDOHR Verdauungs werkz. d. Ins. s. 204, 205, TREVIRANUS Verm Schr. I. 
s. 29—31, Tab. m1. figs. 16, 17, TULK in Ann. of nat. Hist. x11. 1843, pp. 246—248. 
PIR. Hey 07 
2 TREVIRANUS, in his work Ueber den innern Bau der Arachniden, s. 29, 30. Tab. 
11. fig. 24, has described the intestinal canal imperfectly. Branpr Mediz. Zool. 1. 
has partially improved on him. We follow here especially WasmMANN in Abhand- 
lungen herausgegeben von den naturwissensch. Verein, Hamburg, 1846. I. 4to. s. 142— 
144. 
3 Syst. der vergl. Anatom. Iv. 8. 145. 
4 J. MvEnuER in Mecker’s Archiv f. Anat. u. Physiol, 1828. 8. 2. 
