OF THE ORDER ARANEIDEA. 255 
of turmeric paper is rendered brown by the applica- 
tion of the fluids from the mouth and stomach, and 
that it is restored again by the agency of the fluid 
secreted by the poison-glands, changes which afford 
another proof, in addition to those already advanced, 
of the respective alkaline and acid properties of these 
animal products. 
The instruments employed by the Araneidea to 
seize and destroy their prey are improperly denomi- 
nated mandibles; I say improperly, because they 
actually do not constitute any part of the oral appa- 
ratus, as Mr. W. S. MacLeay has plainly asserted + ; 
indeed many eminent zootomists, judging from their 
position and from the origin of the nerves distributed 
to them, entertain the highly probable opinion that 
they are the analogues of the antenne of hexapod 
insects, and in accordance with this view of the sub- 
ject M. Latreille termed them chelicera; but so widely 
do they differ from antenne in structure and func- 
tion, that the propriety of bestowing upon them a 
distinct appellation which does not imply any thing 
hypothetical will scarcely be questioned: I propose, 
therefore, to name them falces. 
Much of the misapprehension that exists among 
arachnologists relative to the falces has been occa- 
sioned, in all probability, either by the prevailing 
+ ‘Annals and Magazine of Natural History,’ 1839, vol. ii. 
p. 2, note *. 
