WEB-SPIDERS. 



225 



enough to be overpowered, and travellers report having found small birds in their 

 clutches. When laid, the eggs are wrapped in a strong cocoon, which the mother 

 guards in her nest. 



The bird-eating spiders inhabiting the countries lying between India and 

 Queensland differ from those coming from Africa and America in possessing sound- 

 producing organs, which lie between the outer surface of the mandible and the 

 inner surface of the maxilla or basal segment of the palp. In one case, namely, 

 in the subfamily Selenocosmiince, the outer surface of the mandible is furnished 

 with spines, and the inner surface of the .maxilla with a set of horny notes, of 

 varying thickness and length, which are thrown into a state of vibration by being 



BANDED BIRD-EATING SPIDER (Pcecilotherio, fasciata). 



rubbed over the spikes on the mandible. This organ is equally well developed in 

 both males and females, and appears in the young soon after they emerge from 

 the eggs. When these spiders are irritated or alarmed, they raise themselves upon 

 their hind-legs and, by waving the palpi, scrape the keys against the spines on 

 the mandibles and produce a sound which has been described as resembling the 

 dropping of shot upon a plate. It is probable that the sound thus produced acts 

 for the benefit of the spider in warning other creatures. In the second group 

 (Ornithoctonince) the notes, formed of feathery hairs, are situated on the outer 

 surface of the mandible, and the spines on the inner surface of the maxilla. 



Nearly allied is the family Dipluridce, differing in having three well-developed 

 claws upon the feet, and the external spinning mammillae exceedingly long. Its 

 members differ in habits, spinning upon the ground wide sheet-like webs to ensnare 



VOL. vi. 15 



