568 PROCEEDINGS OF THE ACADEMY OF [Dec, 



by keeping these spiders in cages that the makers of these cocoons 

 were determined. One cocoon that I opened contained only 13 eggs. 



Prosthesima atra (Hentz). 



These common drassids live beneath stones in small, thin-walled 

 nests. A remarkable habit was seen on several occasions during the 

 nest-making in cages : the spider spins first upon the floor of the cage 

 beneath her, then at intervals stands nearly vertical with the head down 

 rotating the elevated abdomen on its pedicel, or else bending it quickly 

 from side to side ; the abdominal apex then describes circles in the air 

 with the spinnerets actively moving. This is done for a few seconds 

 at a time, and alternated irregularly with spinning on the floor. Such 

 an attitude has not been seen by me before. Is it an attempt to find 

 some roofing object against which to spin, or is it a throwing or casting 

 of a line? Emerton (/. c.) has observed that the "cocoon is fiat on 

 one side, by which it is attached, and convex on the other. It is 

 white, or sometimes a little pink." The cocoon is sometimes, but not 

 always, thinly covered with foreign particles, and is guarded by the 

 mother, who rests upon it ; but she does not hold it nearly so tenaciousl} r 

 as Drassus does. Wild cocoons are found first in the early part of 

 August, and sometimes two are found superimposed. 



Poecilochroa. 



A female of P. variegata (Hentz) was placed in a vial, where she 

 made an incomplete nest at one end. On 27 July at 7.30 A.M. she was 

 standing in a small cell within this nest upon a nearly completed 

 cocoon-base ; this base was thin, roughly circular in outline, its diameter 

 about one and a half times her body length, and placed almost vertical, 

 with its margins fastened to the inner wall of the nest. She oviposited 

 upon the centre of this base from 8.02 to 8.04, then spun until 9.15 

 constructing the cover. Until 1 September, when the young emerged, 

 the cocoon remained in the same position, attached by its edges to 

 the nest, with the mother holding it continuously. A female of 

 P. bilineata (Hentz) was caught on 11 July, and on the night of 13 July 

 made a cocoon : a flattened circular disc, placed horizontally, its diameter 

 greater than her length with outstretched legs, its color glistening 

 ivory-white with a pearly lustre. She subsequently made a closed 

 nest around it, did not change its position, but remained upon it; she 

 left the nest for the first time four weeks later, but returned to it ; the 

 young hatched 17 August. A wild cocoon of this species contained 

 22 eggs. 

 Range of Architecture in Drassids. — The observations just described 



