ARACHNIDA 77 



CYCLOSA CAUDATA. 



Most abundant on the lava fields of Albemarle north and east of 

 Tagus Cove and w^est of Elizabeth Bay, and on Narboro along the 

 east shore ; a few^ found in the brushy vegetation immediately about 

 Tagus Cove ; rare at James Bay on James Island and on the southern 

 Seymour Island; found elsewhere only on Hood. On the last island 

 there are no open lava fields. The species, though not abundant on 

 Hood, was not scarce, and its webs were nearly always to be found in 

 open rocky places. 



In its habits this species, on the Albemarle and Narboro lava fields, 

 was almost gregarious, for wherever found there were generally pres- 

 ent in the immediate vicinity a large number of individuals. They 

 constructed their webs under projecting ledges of lava, between neigh- 

 boring lava blocks, amongst the multitude of sharp pinnacles and 

 rough prominences of the lava surface, but especially in the fissures of 

 the lava. In fissures three to four feet wide often a great many webs 

 occurred close to and parallel with one another stretched across from 

 one side to the other. In one such crack in the lava field, inland about 

 a mile from Tagus Cove, were counted fifty parallel webs of this 

 species in a length of about fifteen feet. 



The webs are vertical orbs generally supported above by a thick, 

 straight, horizontal line having accessory stay lines running from it to 

 the webs at the sides of and below the orb. The spider occupies the 

 center of the orb, and usually, not always, when approached, first 

 rapidly vibrates the web, then if the intruder approaches still nearer 

 and attempts to molest the spider or even touches the web, ascends to 

 the upper horizontal line and runs along this toward the support at 

 one end. If still further annoyed the spider closes its legs beneath the 

 body and drops to the ground, where it relies for protection on its re- 

 maining motionless and on its resemblance to the particles of lava and 

 soil amongst which it has fallen. 



Egg cocoons were found in several webs at Tagus Cove, in March. 

 The cocoons were elongate papery cases attached to a thick vertical 

 thread, running from the center of the orb in some cases to the upper 

 horizontal line, and in others to a support several feet above the 

 orb. 



ARGYROEPEIRA NIGRIVENTRIS. 



A rare Galapagos species. Found on Albemarle only in the man- 

 grove swamps west of Elizabeth Bay. The Narboro specimen was 

 taken on the southeast slope of the central mountain at an elevation 



