$Amaurobius sylvestris.$--This is the common Amaurobius all over the northern part of the country. It resembles our species of Tegenaria (figs. 228, 233) and may easily be mistaken for them. It does not have long upper spinnerets like Tegenaria, and the eyes are lower on the front of the head. The females (fig. 489) are two-fifths of an inch long, and the males a third of an inch, but with much longer legs. The head of the female is almost as wide as the middle of the thorax, and the eyes cover half its width. The front row of eyes are within their diameter of the front of the head. The head is low in front and higher halfway between the eyes and the dorsal groove. The mandibles are much swelled at the base in front, as they are in _Tegenaria medicinalis_. The abdomen is oval, widest behind, and usually as long as the cephalothorax or longer. The legs are not more than a fourth longer than the body, and slender for so large a spider. The cephalothorax is dark brown, darkest in front, and the legs are a little lighter brown, without markings. The abdomen is gray, with a double row of oblique yellow or white markings on the hinder half and two curved marks of the same color on the front. These spots sometimes run together, so that the whole middle of the abdomen is light colored. The males have the head narrower and the thorax wider and all the legs longer than the female, and the cephalothorax and mandibles are not so dark colored. The male palpi have the patella as short as wide, and the tibia very short and wide, with a short hook on the outer and a longer and more slender one on the inner side, as shown in fig. 490. The epigynum has a small middle lobe inclosed by two lateral lobes that meet behind, and by this the female can be distinguished from the next species,--_Amaurobius ferox_. The cribellum (fig. 469) is sometimes covered by a fold of the skin, so that it is not readily seen. The calamistrum (fig. 470) is a close row of curved hairs on the upper side of the fourth metatarsus, about half its length. In the male the cribellum is rudimentary, and there is no calamistrum. [Illustration: FIG. 491. Fresh part of the web of Amaurobius sylvestris.] 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). [Illustration: FIG. 492. Tibial joint of male Amaurobius ferox for comparison with that of Amaurobius sylvestris (fig. 490).]