APPENDAGES 32 1 



while the chelicerae are pushed forward, no orifice is visible, but 

 on careful examination it will be found that what appears to be 

 a thick and fleshy labium is, in reality, two organs. The labium 

 is thin and flat, and closely opposed to its upper surface is a 

 somewhat flattened cone. This is the " rostrum," and when it 

 is separated from the labium the buccal orifice is disclosed. 

 In a few spiders (Archeidae) in which the chelicerae are far 

 removed from the mouth, the rostrum is tolerably conspicuous, 

 but in most it is so hidden as to have escaped the observation of 

 the great majority of observers. Schirakewitsch considers it 

 homologous with the labrum of insects, but Simon thinks that 

 it represents all the insect mouth-parts reduced to an exceed- 

 ingly simple form. It is more probable that a beak consisting 

 of a simple labrum and labium was a primitive Arachnid char- 

 acteristic. If the rostrum be removed and its inner (or posterior) 

 surface examined, a lance-shaped chitinous plate, the " palate," 

 becomes visible. It is furrowed down the middle by a naxrow 

 groove, which is converted into a tube for the passage of fluids 

 when the rostrum is opposed to the labium. 



Pedipalpi. — The pedipalpi are extremely leg-like feelers, and 

 are six-jointed, the metatarsal joint of the ambulatory legs being 

 absent. The joints, there- ^^ 



fore, are the coxa, trochanter, /i^l^ 



femur, patella, tibia, and I'lllli^^ 



tarsus (Fig. 178).^ | m^f 



In the Theraphosae the \ \l|Ji§^! ^ 



coxa resembles that of the \^\W^ 



ambulatory leg, but in other \^-~^^.^/ " #y / 



spiders it is furnished, on ^^'^o v \K\:VS\\ vw 

 the inner side, with a blade- ^^^^^^^M(^"'^ 



like projection, the " maxilla " 5'' -^^M^^^r/'^ /\r'T^ 



(Fig. 178). The shape of the \ ^ \ 



° Fig. 178. — Fedipalp of Tegenaria domestica S ■ 



their inclination towards the x 5. 1, Coxa ; 2, maxilla ; 3, troolianter ; 



labium are_ of considerable 3^; ^-- ^^^P^**^"^ ■ «' «bia ; 7, tarsus ; 



taxonomic importance. The 



inner border of the maxilla is furnished with a tuft of hairs, 



1 Pickard-Cambridge {Spiders of Dorset, 1879-1881) omits the coxal joint, which, 

 with its lobe, he calls the maxilla, and therefore gives only five joints, which 

 he names axillary, humeral, cubital, radial, and digital. 



VOL. IV Y 



