$Erigone longipalpis$ and $dentigera.$--These spiders are a tenth of an inch to a twentieth of an inch long and generally dark brown in color, with the cephalothorax smooth and shining. In some, especially the larger males, the cephalothorax is bright orange and the legs partly of the same color. The females vary considerably in size, but are otherwise much alike. The peculiarities are in the males. The head is about half the length of the cephalothorax and abruptly raised and rounded on the top (fig. 361). Along the sides of the thorax are small pointed teeth of various sizes in a single irregular row (fig. 362). The mandibles are very much thickened in the middle and have a row of teeth on the front outer side (fig. 364). The palpi of the males are sometimes as long as the whole body and of a complicated shape. The femur is curved upward and forward and has a row of little teeth on the under side. The patella and tibia are together about as long as the femur. The patella has at the end a straight tooth directed downward with a short point (fig. 361). The tibia is widened at the end, where it spreads around the base of the tarsus. The maxillæ are much thickened and the bases of the palpi spread wide apart (fig. 365). The palpi are usually carried doubled up in front of the head, with the curved ends of the femora just below the eyes and the palpal organs over the ends of the mandibles. The legs of Erigone are only moderately long, and they walk easily, like the small Drassidæ. They move slowly and are not easily frightened, so that at the time of flying they can be closely watched. [Illustration: FIGS. 366, 367. Erigone autumnalis.--366, under side of cephalothorax of male. 367, palpus of male.] $Erigone autumnalis.$--This is one of the few species of Erigone that can be distinctly separated from the others. It lives in the same places and is found with _longipalpis_ in the autumn flights. It is only a twentieth of an inch long, but can be distinguished by its light color and bright yellow head. The palpi of the males have the tibia shorter than the patella and the tooth on the patella turned more forward than in _longipalpis_, with a longer and sharper point tapering from the base to the tip (fig. 367). [Illustration: FIGS. 368, 369, 370. Ceratinella lætabilis.--368, outline of side of female enlarged sixteen times. 369, 370, end of male palpus.]