THE GENUS ACROSOMA

These are small spiders, with the abdomen extended back half its length beyond the spinnerets, brightly colored, flattened above, and furnished with several pairs of pointed processes. The cephalothorax is longer than in Epeira and Argiope and widest in the middle. The legs are slender and have only fine and soft hairs. The webs [(fig. 437)] are inclined and have a hole in the middle surrounded by several turns of smooth thread; when hanging in it the spiders look like burrs or seeds. At a slight alarm they will sometimes drop to the ground and hide under the nearest shelter.

Acrosoma mitrata.—This is a smaller species than rugosa or spinea. The abdomen does not extend as far backward as in the other species, but comes farther forward so as to cover half the cephalothorax [(fig. 438)]. The abdomen is truncated behind, with two pairs of pointed processes at the corners, one pair below the other. In front, the abdomen is a little narrowed over the thorax. The legs and cephalothorax are brown, as in the other species. The abdomen is light yellow, darker behind, with two or three pairs of black spots along the middle and five or six dark elongated spots along the sides. The under side is black mixed with yellow spots, as in the other species. Common as far north as Connecticut.