36 RIO DE JANEIRO. [CHAP. ir. 



backs, having gregarious habits. The webs were placed vertically, 

 as is invariably 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 bushes 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 saire species with mine. I cannot, 

 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 gregarious 

 habit, in so typical a genus as Epeira, among insects, which are so 

 bloodthirsty and solitary that even the two sexes attack each other, 

 is a very singular fact. 



In a lofty valley of the Cordillera, near Mendoza, 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, instead 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. 



