THE AERIAL WEB SPINNERS 167 



only a single palpus, a large bulbous affair, the mate of which is 

 extirpated just before full maturity. 



Remarkable for their social habits are the species of Anelosimus, 

 close relatives of the theridions but having more elongate bodies. 

 Our single well known species, studiosus, is a light brown spider 

 one sixth of an inch long with dark upper and lower stripes on the 

 abdomen. It is abundant in the South, and occurs as far north as 

 New Jersey. Its communal web is placed on shrugs and trees, and 

 ordinarily comprises an unsightly mass of dead leaves tied together 

 with silk and serving as a retreat, around which extends a sheet of 

 silk attached to twigs. Several individuals live together in the nests, 

 which, except for size, are like those of other gregarious species. A 

 very similar species abundant in Brazil, Venezuela, and Panama is 

 Anelosimus eximius, once dubbed socialis and well known for its 

 social habits. Colonies of hundreds or thousands of individuals, 

 males and females and immature stages, spin a light, transparent 

 web, similar in texture to the sheets of the grass spiders, which has 

 little definite form and may completely invest sizable shrubs and 

 even trees. Some are a yard across, and are spun fourteen or fifteen 

 feet up into the foliage of trees. The spiders wander about freely 

 within these confines, and feed communally on insects that are 

 captured at the periphery of the web and carried into the interior. 

 Sometimes found in the webs are such vagrant spiders as Sergiolus 

 and the two-eyed Nops; they may be predators or perhaps sym- 

 bionts, but their exact relationship to the aggregation is not known. 



One group of theridiids deserves mention both for curious body 

 forms and for commensal habits. These spiders are mostly small, 

 and, except for the vermiform types, rarely exceed a third of an 

 inch in length. Their legs are long and very unequal, and the tarsal 

 claws are remarkable in that the unpaired one is long, only slightly 

 curved, and may actually exceed the paired claws in length. The 

 tarsal comb is reduced to three or four modified setae. Both the 

 cephalothorax and abdomen are subject to curious variations within 

 the three known genera. In Ariamnes, the abdomen is drawn out 

 into a long and slender cylinder that ends in a point; in Rhomphaea, 

 it is usually triangular in shape, sometimes extremely high, and oc- 

 casionally vermiform as in the preceding genus; in Conopistha, the 

 abdomen takes many forms, being spherical, triangular, or cylin- 

 drical, and embellished with lumpy or pointed projections. In both 

 Rhomphaea and Conopistha the heads of the males are ornamented 



