THE TARANTULAS 115 



lack the rows of spines that the other group has, possessing instead 

 a light-to-heavy scopula of hairs on the distal segments. 



The open door of torreya appeals to us as being virtually an 

 invitation to enter. Atkinson, who studied a similar species in North 

 Carolina, thought that the principal chamber was intended as a 

 prison for ants that wandered in and were captured after closing 

 the inner door. He called the genus Myrmekiaphila because these 

 spiders build their nests near or even in anthills, and he believed 

 that the ants make up a large part of the tarantula's food supply. 

 Moggridge interpreted similar nests in terms of a protective device. 

 A wasp, intent on paralyzing the spider and placing an egg on its 

 body, finds a trap door, which may be open or which she may 

 open or force, and enters in search of the spider. The spider mean- 

 while rushes to the bottom of the burrow and closes the main tube 

 with the inner trap door. Should the wasp persist, the spider crawls 

 into the side chamber, moving the dual-purpose door to protect 

 that opening. Once the main tube has been fully explored and 

 found empty, the wasp may leave without discovering the inner 

 chamber. 



Cyclocoswia truncata is a trap-door spider remarkable for the 

 peculiar shape of its abdomen, and interesting in that it had been 

 considered by many as the rarest spider in North America. It is a 

 large, fat creature, rather closely related to Pachylomerus except 

 for the abdominal structure. This round, leathery, caudally trun- 

 cated organ, in the absence of actual observations, had led to in- 

 triguing conjectures as to what use it is put by the spider. 



The initial description of truncata was made by Nicholas Mar- 

 cellus Hentz, the father of American araneology, who in 1841 gave 

 it the name of My gale truncata. His specimens, all of which were 

 females and all since lost, came from Alabama. In his words: 

 ". . . this spider dwells, like other species of this subgenus, in cylin- 

 drical cavities in the earth. Though many specimens were found, 

 I never saw the lid described by authors as closing the aperture of 

 its dwelling. The very singular formation of its abdomen, which 

 is as hard as leather behind, and which forms a perfect circle, in- 

 duces me to believe that it closes with that part, its dwelling instead 

 of with a lid, when in danger." What Hentz meant by "the lid 

 described by authors" is inexplicable, unless he was referring to the 

 lids of nests of closely related spiders, since, to our knowledge, he 

 was the first man to see and record the species. Along with draw- 

 ings of the animal, Hentz included a sketch of "the hole in which 



