Superfamily Avicularioidea 



Fig. 214. CHELICERAOF PACHY- 

 LOMERUS SHOWNG THE RAKE 



and in almost always having the third claw well-developed; and 

 they differ from the web-making tarantulas in having the chelicera? 



furnished with a rake (Fig. 214). 



The lack of the bundle of termi- 

 nal tenent hairs on the tarsi is cor- 

 related with the sedentary habits 

 of these spiders; the possession of 

 a third claw aids them in climbing 

 up the sheet of silk with which they 

 line their burrows; and the rake 

 of the cheliceras serves to dislocate 

 the earth, when digging their bur- 

 rows, and to make it into a ball, 

 which they throw up with their hind 

 legs; these are strong and armed 

 with strong spines. 

 To this subfamily belong the larger number of the taran- 

 tulas that have attracted attention on account of their architec- 

 tural skill. They dig tunnels in the ground, which, in most 

 cases, are closed with a hinged lid (Fig. 215); this fact has sug- 

 gested the popular name of trap-door spiders, which is applied 

 to them. 



After the tunnel is dug, the wall is usually coated with a 

 coat formed of earth and saliva. Inside of this wall there is spun 

 a layer of silk, which sometimes hangs free, but usually adheres 

 to the earth. Sometimes the silken lining is restricted to the 

 upper portion of the tunnel. 



The wall of the tunnel is usually 

 so firm, perhaps owing to the earth 

 being cemented in some way, that 

 the nest retains its form when the 

 surrounding soil is dug away. 



Different types of nest are made 

 by the different species. In a few 

 cases the mouth of the tunnel is open; 

 but as a rule it is closed by a lid or 

 door. The nests also differ in three 



other particulars: first, the tunnel may be either simple or 

 branched; second, the door of a closed nest may be a simple 

 flap of silk and dirt, the wafer type (Fig. 213), or it may be a 



Fig. 215. ENTRANCE TO 

 TUNNEL OF TRAP-DOOR 

 SPIDER, THE WAFER TYPE 



232 



