152 

 Tribe II. Paktitje. External eyes apart. 



22. Theridion trigonum. 



PI. 16, figs. 24, 25. 



Description. Pale brown or yellowish: lower middle eyes 

 borne on tubercles; abdomen triangular, with changeable 

 rufous lines, chiefly on the sides ; male rufous, abdomen trian- 

 gular, narrower behind ; feet 1. 4. 2. 3, or 1. 2. 4. 3. A small 

 species. 



Observations. This species, though varying much in color 

 and marking, is at once recognized by the form of its abdomen, 

 which, when viewed sideways, appears three-sided. It makes 

 the usual web of Theridion, but sometimes it has an additional 

 web, like that of Linyphia. It is found very common in 

 autumn, constantly in an inverted position in the middle of its 

 web. Its cocoon is of a very singular shape, being orbicular 

 and sometimes ovoid, with a neck turned downward, like an 

 inverted gourd, and suspended by a thread attached to the web. 

 One of those cocoons being opened was found to contain the 

 pupa of an hymenopterous insect, a parasite. 



Habitat. Alabama. July-September. 



[PI. 19, fig. 117, lateral view ; fig. 131, cocoons. Abdo- 

 men beneath variegated with rufous. Supplement.'] 



[?, length 4.2 mm. ; cephalothorax 1.1 mm. ; legs 7.2, 5, 3, 5. 

 cf, " 2.5 mm.; " 1.1 mm. ; legs 8.2, 5.6, 3, 5. 



PI. 21, fig. 14, palpus of 8. 



The end of the abdomen is not pointed like fig. 25, pi. 16, but notched, 

 and in some specimens the two points are turned outward. Specimens in 

 alcohol sometimes contrast like pi. 19, fig. 117. Tne end of the abdomen 

 can be curved downward toward the spinnerets, and this is sometimes done 

 when the web is disturbed. 



Beverly, Mass., May 10, on a birch twig, with an irregular web ; June 18, 

 in the upper part of a web of Linyphia scripta; July 16, 6 and 5, among 

 the upper threads of a web of Agelena ncevia ; Ilolyoke, Mass., July 4, ?, in 

 a tent made of one birch leaf hung in an irregular web; Peaks Island, Port- 

 land, Me., Aug. 11, cocoons of eggs on spruce trees. J. n. E.] 



