XVI APPENDAGES 



433 



projection, the " galea," arising at its base, and extending beyond 

 the joint in front. In the Obisiinae it is only represented by a 

 slight prominence. 



Two other organs characterise the chelicerae of all the 

 Chernetidea ; these are the " serrula " and the " flagellum." 

 Their minute size and transparency make them very difficult of 

 observation, and for a long time they escaped notice. The 

 serrula is a comb-like structure attached to the inner side of the 

 distal joint. The flagellum is attached to the outer side of the 

 basal joint, and recalls the antenna of a Lamellicorn beetle, or the 

 " pectines " of scorpions, a resemblance which gave rise to the 

 supposition that they are olfactory organs. It is more likely, 

 however, that they are of use in manipulating the silk. 



The pedipalpi are six-jointed and are very large, giving these 

 animals a superficial resemblance to scorpions. According to 

 Simon,^ the patella is absent, and the joints are coxa, trochanter, 

 femur, tibia, tarsus, with an apophysis forming the fixed digit of 

 the chela, while the sixth joint is the movable digit, and is 

 articulated behind the tarsus. These joints, especially the 

 tarsus, are often much thickened, but however strongly de- 

 veloped, they are always narrow and pediculate at the base. 

 The coxae of the pedipalps are closely approximated, and are en- 

 larged and flattened. They probably assist in mastication, but 

 there is no true maxillary plate articulated to the coxa as in 

 some Arachnid groups. 



The legs are usually short and feeble, and the number of their 

 articulations varies from five to eight, so that it is not easy to 

 be certain of the homologies of the individual joints to those of 

 other Arachnids. The coxae are large, and form thp floor of the 

 cephalothorax. They are succeeded by a short trochanter, which 

 may be followed by another short joint, the " trochantin." Then 

 come the femur and tibia, elongated joints without any inter- 

 posed patella, and finally the tarsus of one or two joints, ter- 

 minated by two smooth curved claws, beneath which is situated 

 a trumpet-shaped membranous sucker. 



Internal Structure.^ — The internal structure of the Cherne- 

 tidea, as far as their small size has permitted it to be made out, 

 bears a considerable resemblance to that of the Phalangidea. 



^ Arachiiides de France, vii., 1879, p. ^>. 

 2 See Bernard, J. Linn. Soc. xxiv. (Zool.), 1893, p. 410. 

 VOL, IV 2 F 



