422 



ARACHNIDA 



6. THERIDION Walckenaer. Anterior row of eyes straight or nearly 

 so; the 2 middle pairs of eyes of the same size, and equidistant from 

 one another: about 40 American species. 



T. tepidariorum Koch (Fig. 664). Body 6 mm. long, varying in color 

 from whitish to black ; cephalothorax usually 

 light brown, the dark individuals with 6 

 transverse black marks on the abdomen : a 

 cosmopolitan species and one of the common- 

 est house spiders, being chiefly responsible 

 for the webs in the corners; it breeds sev- 

 eral times a year and the young and old 

 are found at all seasons. 



T. frondeum Hentz. Body 3 mm. long, 

 and white or bright yellow in color, with 

 very variable black markings on the back, 

 which may consist of 2 rows of spots or a 

 median band: in bushes; common. 



T. differens Emerton. Body about 3 

 mm. long; abdomen round, reddish-brown, 

 with a red median stripe having white 

 edges, which is bright in the female and 

 obscure in the male ; sternum orange : web on 

 low plants, 5 or 6 inches in diameter. 



T. murarium Em. Body about 4 mm. long; abdomen round, gray in 

 color, with a reddish median stripe, white on the edges; sternum pale, 

 with a black edge and a black median stripe: on low bushes. 



FAMILY 8. LINYPHIIDAE. 



Small spiders with an elongate but high abdomen; mandibles with 

 teeth around the terminal claw ; epigynum and male appendages large and 

 complex : web consists of a flat or curved sheet of silk supported above and 

 below by great numbers of threads and found either in open woods or near 

 the ground in grass and dead leaves, or in caves or cellars. The smaller 

 species have the curious habit of flying in the late autumn. They come to 

 the tops of fences and other elevated objects and cause their silk to be 

 drawn out and floated aloft by the currents of air, until they are themselves 

 lifted up and often blown long distances; about 95 American species. 



Key to the genera of Linypliiidae here described : 

 #! Female with a terminal claw on the pedipalp. 

 bi Hinder pair of median eyes not close together. 1. LINYPHIA 



6 2 Hinder pair of median eyes close together 2. LEPHTHYPHANTES 



o 2 No such terminal claw. 



&! No hard plate on the abdomen 3. ERIGONE 



6 3 Abdomen covered by a hard plate 4. CERATINELLA 



Fig. 664 Theridion tepida- 

 riorum (Emerton). A, the 

 spider; B, its web. 



