i88 AMERICAN SPIDERS 



United States, but most live in the tropics, where an amazing array 

 of bizarre types has developed. The genus Gasteracantha is poorly 

 represented in the Americas; only three or four extremely variable 

 species are found. The genus Micrathena, comprising more than a 

 hundred long-bodied species, with flat or elevated abdomens bor- 

 dered by long spines or thick spurs, is exclusively American. 



The spiny-bodied spiders hang on short legs in the centers of 

 their webs, looking rather like chips of wood, bits of leaf, or plant 

 fruits. The sharp spines make them unpleasant morsels for birds, 

 lizards, and vertebrate animals, but their worst enemies, the solitary 

 wasps, fill mud cells with them, not at all deterred by the armor. 

 G aster acanthus webs are inclined or vertical, and have open hubs. 

 The radii or foundation lines are ornamented with a series of floc- 

 culent tufts of whitish silk. It has been suggested that these may 

 serve as lures for midge-eating insects, which, deceived by the white 

 flecks, might fly into the orb and be caught. 



Two species of Gasteracantha are found in the United States, 

 but one, tetracantha, is very rare. The other, Gasteracantha cancri- 

 formis (Plate 14), is common in the southern states. It is subject to 

 considerable variation. It has a yellowish or orange abdomen 

 spotted with black and fringed by six spines. 



Our species of Micrathena are equally spectacular in their bright 

 coloration and curious shapes. Micrathena saghtata (Plate 22), an 

 arrowshaped species having a white or yellow abdomen armed with 

 a tiny basal and median pairs, at the apex a greatly enlarged pair, 

 of divergent redtipped spines, is common even in the Northeast. 

 Lumpy Micrathena gracilis, a light brown species, whose elevated 

 abdomen is set with five pairs of short spines, is representative of 

 a quite different series. These, and others not mentioned here, have 

 small males that in shape do not closely resemble the females. 



The typical orb weavers of the subfamily Araneinae so far out- 

 number those of other subfamilies that in the temperate regions 

 they are the dominant group. Their physical characteristics are a 

 generally thick-set appearance, bulky abdomens and relatively short 

 legs, but some have become elongate types that can run quite 

 rapidly. The abdomens of the typical orb weavers are subject to a 

 very considerable variation in shape. Some are leathery, and sur- 

 mounted by humps or spines that make them resemble those of the 

 spiny-bodied spiders, from which they differ in not having the spin- 

 nerets on the end of a tubular eminence. Sexual dimorphism is 

 pronounced in many genera, especially in the bolas spiders; in cer- 

 tain cases the males may be essentially equal in size to the females, 



