Theridium unimaculatum.—This little species differs in color and markings from all the others, and may almost always be distinguished by the white abdomen, with a black spot in the center of the back. The females are a twelfth of an inch long and the males smaller. The cephalothorax is orange yellow, with a black spot around the eyes, extending back in a point as far as the dorsal groove, and there is also a fine black line along the edges. The legs are orange, lighter in the female and darker in the male, with the first and second pairs in the male much stouter. The sternum is orange, with black edges. This spider makes a web, like the other small species, among small leaves and winters under dead leaves on the ground.

THE GENUS STEATODA

Steatoda has the legs shorter and stouter than Theridium. The abdomen is oval and often a little flattened on the back. It is smooth and shining, the hairs being fine and scattered so as to be hardly visible. The thorax is thick and hard, and in some species marked with hard projections and depressions. The head is generally narrow, and the front middle eyes are in several species larger than the others and farther forward and wider apart. In other species all the eyes are about the same size. The webs consist of a flat sheet supported and held down by threads.

Steatoda borealis.—This is a dark reddish-brown spider, quarter of an inch long, living among stones or in the corners of fences and window frames, generally well concealed by its web or nest. The cephalothorax is orange brown and covered with short stiff brown hairs. The head is one-third as wide as the thorax and a little higher, the eyes near together, with the front middle pair projecting forward beyond the mandibles [(fig. 279)]. The legs are brown, with faint darker rings, and are thickly covered with hairs. The abdomen is dark chocolate brown, sometimes without any light marks on the upper side, but usually there is a light line running around the front half and another in the middle, extending back half the length of the abdomen and usually broken into several spots. The four depressed spots on the abdomen are distinctly marked. On the under side there is a light stripe on each side, meeting behind the spinnerets. The sexes are much alike in size and color, but the palpi of the male [(fig. 278)] are longer than the cephalothorax, and the terminal joint is very large and complicated. The web consists of a flat sheet, held out by threads in all directions, but is often so crowded into a corner that its structure is hard to understand [(fig. 276)].