48 RIO DE JANEIRO. 



I may here just mention, that I found, near St. F^ 

 Bajada, many large black spiders, with ruby-col- 

 oured marks on their backs, having gregarious 

 habits. The webs were placed vertically, as is in- 

 vai'iably the case with the genus Epeira: they were 

 separated from each other by a space of about two 

 feet, but were all attached to certain common lines, 

 which were of great length, and extended to all 

 parts of the community. In this manner the tops 

 of some large bvishes were encompassed by the 

 united nets. Azara* has described a gregarious 

 spider in Paraguay, which Walckenaer thinks must 

 be a Theridion, but probably it is an Epeira, and 

 perhaps even the same species with mine. I can- 

 not, however, recollect seeing a central nest as large 

 as a hat, in which, during autumn, when the spiders 

 die, Azara says the eggs are deposited. As all the 

 spiders which I saw were of the same size, they 

 must have been nearly of the same age. This gre- 

 garious habit, in so typical a genus as Epeira, 

 among insects, which are so bloodthirsty and soli- 

 tary that even the two sexes attack each other, is a 

 very singular fact. 



In a lofty valley of the Cordillera, near Mendo- 

 za, I found another spider with a singularly-formed 

 web. Strong lines radiated in a vertical plane 

 from a common centre, where the insect had its 

 station ; but only two of the rays were connected 

 by a symmetrical mesh-work; so that the net, in- 

 stead of being, as is generally the case, circular, 

 consisted of a wedge-shaped segment. All the 

 webs were similarly constructed. 



* Azara's Voyage, vol. i., p. 213, 



