Superfamily AviculariciJ.a 



In the Avicularioidea the chelicerae project forward and the 

 claw of the chelicera moves vertically (Fig. 211); the pedipalps 

 (Fig. 212) are not furnished with a well-developed endite, except 

 in the Atypidae; and there are two pairs of book-lungs (Fig. 129). 



The characters pre- 

 sented by the chelicerae 

 are distinctive; but the 

 number of the book- 

 lungs is not quite so, for 

 in one small family, the 

 Hypochilidae, belonging 

 to the other superfamily, 

 two pairs of book-lungs 

 are present. 



The Avicularioidea 

 includes two families, 

 the Aviculariidae and the 

 Atypidae; the Avicula- 

 riidae is well represented 

 in our fauna, nearly 

 two score species hav- 

 ing been described from 

 the southern and western 

 portions of the United 

 States. But of the Atypidae only two species have been found 

 in this country. 



Fig. 212. PEDIPALP OI EURYI'ELMA 



Family AVICULARIID^ (A-vic-u-la-ri'i-dae) 



7 /'c Typical Tarantulas 



The typical tarantulas are distinguished from all other 

 spiders by the form of the coxa of the pedipalps, which resembles 

 the coxae of the legs in lacking a distinct endite. In the next 

 family, the Atypidae, and in the true spiders, the Argiopoidea, 

 the coxa bears a plate, the endite, which is the crushing part of 

 the organ. It should be stated, however, that in a few of the 

 typical tarantulas the coxa of the pedipalps bears a small lobe 

 which is really a small endite (Fig. 212). 



The bulb of the palpus of the male is comparatively simple 

 in structure (Fig. 213); it is described in an earlier chapter (p. 109). 



229 







