This spider makes a large loose web under stones and sticks [(fig. 488)]. In the parts freshly made the loose bands of silk can be seen running irregularly about on the other threads [(fig. 491)].

Amaurobius ferox.—This lives in houses and is probably an imported species, as it is more common in Europe. It grows a little larger than sylvestris [(fig. 489)], and the head is a little more narrowed in front of the legs. The colors and markings are much as in sylvestris, but the abdomen is often darker, and the middle light stripe on the front more distinct. The epigynum has a larger middle lobe, and the lateral lobes are straighter and do not meet in the middle. The males are colored like the females and have the thorax wider and the legs longer. The palpi of the male have the tarsus short and round. The tibia [(fig. 492)] has only a small short hook on the inner side, and a large blunt process on the outer side. The male palpi and the epigynum distinguish these easily from the last species.

Amaurobius (Titanœca) americana.—Quarter of an inch long and deep black, except the cephalothorax, which is dull orange color, but covered, like the rest of the body, with long black hairs [(fig. 493)]. Some individuals have a few light gray spots in pairs on the abdomen. The shape of the cephalothorax and abdomen are like Amaurobius sylvestris, and the legs are of the same proportional length and stouter. The palpi of the female have the tibia and tarsus a little thickened. The metatarsus of the fourth legs has the calamistrum more distinct than in others of the family, and the metatarsus appears thicker up and down than it is sidewise. The male has the legs longer, particularly the first pair, of which the tibia and metatarsus are more elongated than the other joints, and have many small spines on the under side. The male palpi have the tarsus large and round, supported by a wide and very complicated tibia. It lives under stones in the hottest and dryest places.