X. tNTBOBtrCTION. 



the spider, are thought to represent the simple ocelli of the inseot. 

 For my own part, although fully persuaded of the extensive 

 agency (among others) of " Natural selection," and of the truth 

 of " Evolution " I cannot at present see sufficient grounds for the 

 above hypothesis as to their effect in modifying what are now 

 the falces and caput of spiders. 



The Maxillae. 



If a spidor be laid on its back, two elongate pieces will be seen 

 at the fore extremity, just behind the falces (pi. i., fig. 2, a,a, and 

 pi. ii., fig. 2.e,'e') these are called maxilla, or jaws, because they 

 assist in the compression of the spider's prey, and in squeezing 

 out its juices into the throat (or oesophagal tube). The maxillse 

 form the greater part of the posterior boundary of the mouth ; 

 they are variously formed, of great diversity in size, and 

 constitute, in fact, the basal, or supporting joints, of 

 The Palpi. 



These are two in number, and stretch forwards immediately in 

 front of the first pair of legs. PI. i., fig. 1«, (male), and fig. 2 

 o-h. (female). Occasionally (in the Family Therapho sides) the 

 palpi are used, in the female sex, as legs, but most com- 

 monly only as feelers. Instead of seven joints, like the legs, 

 the palpi have but six, including the basal joint or maxilla. 

 They are very varied in length and strength, and in the form of 

 the joints (pi. i., figs, la, 15, 14, 7. PI. ii., figs. \c, 2f, and 

 6, represent the palpi of several different spiders). In all female 

 spiders the extreme (or digital) joint is of simple form, generally 

 ending with a single, curved, and sometimes pectinated claw. In 

 some groups, however, this claw is absent. The last joint but 

 one is called the radial, the next behind it the cubital, then the 

 humeral, and the next (which connects the palpus with the 

 maxilla) is called the axillary joint. The palpi (like the legs) are 

 usually furnished with hairs, bristles, or spines, or with all or 

 some of these. 



In the male spider we observe a remarkable difference in the 

 extreme (or digital) joint of each palpus ; this, instead of being 



