396 SYSTEM OF INSECTS. 
as Decapods ; but when we trace the two anterior pairs of 
apparent legs to their insertion, we find that both pro- 
ceed from the head, which in that genus is distinct from 
the trunk; while the three last pairs, which alone are fur- 
nished with claws, are planted, as legs usually are, in 
the latter part. The first pair represent the ordinary palpi 
of Arachnida, are analogous to the labial ones of Hexa- 
pods, and, as likewise in Phrynus and Thelyphonus, are 
more robust than what are usually taken for the first 
pair of legs; but they differ in being considerably longer, 
and instead of terminating in a chela are furnished with 
a retractile sucker a . The second pair are more slender 
and shorter than the first; they correspond precisely with 
what are deemed the first pair of legs of Octopods and 
Arachnida, and are clearly analogous to the maxillary 
palpi of perfect insects. Whether the base of the first 
pair of these palpi is in any respect analogous to the la- 
bium of insects, (as that of the second seems to be to their 
maxillae,) I am not prepared to assert: it will therefore be 
most advisable to name these palpi anterior and poste- 
rior : but as they evidently proceed from the head in 
Galcodcs, and in that genus are clearly analogous to 
those of the Phrynidca, (which in their turn as clearly re- 
present those of the Aranidea,) it follows that in all they 
are organs of the part representing the head, and there- 
fore not in a primary sense legs; although in a secondary, 
as M. Savigny has proved, they may be so called b . 
1. Araneidea M c L. {Aranea L., Arancida Latr.) 
The Araneidea, or spiders, seem resolvable into two 
* L. Dufour Six Nouvcll. Arachnid. &c. Ann. Gen. des Scienc. 
Physiq. IV. iii. 17- t. lxix./ 7, b. 
b Mem. sur les Anim, sans Vertebr. I. i. 57 — . 
