Superfamily Argiopoidea 



my practice, when showing students this web in the field, to hold 

 a piece of black velvet cloth behind the web. With such a back- 

 ground and with the sunlight falling upon the web, the observer 

 is sure to be filled with enthusiastic admiration. 



The characteristic form of the web is well-shown in Fig. 405. 

 There is a maze of threads extending in all directions, and in 

 the centre of this maze a dome-like sheet from three to five inches 

 in diameter. When at rest, the spider hangs beneath the apex 

 of the dome. Here it waits till some insect whose flight is im- 

 peded by the maze of threads falls upon the dome; the insect 

 is then seized, pulled through the wall of the dome, and destroyed. 

 When the dome becomes badly injured it is pulled down and a 

 new one built. I n the figure there is shown a dense mass of threads 

 extending horizontally a short distance below the dome; this is 

 the remnant of an old dome. 



This is a very common and widely distributed species, both 

 in this country and in Europe. The spiders mature in early 

 summer, and the young can be found in tiny webs in August and 

 September. 



The Sierra Dome Spider, Linyphia litigiosa (L.li-tig-i-o'sa).— 

 In the Sierra Nevada Mountains there is found a species of Liny- 

 phia that makes a web similar to that of the filmy dome spider 

 of the East except that the dome is much larger and slightly 

 flatter (Fig. 406). Although this spider is widely distributed on 

 the Pacific Coast, and occurs in the Coast Range as well as in 

 the Sierras, I suggest the popular name, the Sierra dome spider, 

 on account of its great abundance in the Sierras. Excepting a 

 species of Agelena, this is the most abundant spider found over 

 a very extensive area in these mountains. 



The adult spider measures one fourth inch in length. The 

 cephalothorax is yellow, with a narrow median black line, and near 

 each lateral margin there is a wider but less distinct dark band; 

 the sternum is black. The abdomen is silvery white above marked 

 with dark brown or black; there is a median dark band, from 

 which extend a variable number of more or less distinct oblique 

 lines; near the caudal end of the abdomen, this median band is 

 broader and encloses from one to three pairs of white spots; the 

 lateral aspect of the abdomen is dark marked with three or four 

 oblique white lines on the caudal half and a longitudinal white band 

 on the basal half; the venter is dark marked with white dots 



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