Fig. [203].—Atypus affinis, ♀.
The Atypidae are a small family of six genera, rather closely related to the Aviculariidae, and by some Arachnologists incorporated with them. They may be regarded as the representatives of that family in sub-tropical and temperate regions. In form they are strongly built, with smooth integuments, and their legs are short and powerful. Of the twenty-four species hitherto described almost all belong to the northern hemisphere. Five are natives of Europe, and two are included in the English fauna. The best known is Atypus affinis, which has been found in several localities in the south of England, and which has occurred on the Devil’s Dyke, near Cambridge. The female measures about half an inch in length, the male being smaller. It burrows a deep cylindrical hole at the edge of a grassy or heathery bank and lines it with a loose tube of silk, which extends considerably beyond the orifice of the burrow, either lying flat on the ground, or raised up and attached to the neighbouring herbage. There is no lid, but the upper end of the tube is always found closed, whether by its elasticity or by the deliberate operation of the spider is not known. The animal is nocturnal in its habits. Another species, A. beckii, occurs very rarely in the south of England.
The genus Atypus has representatives in Central and South Europe, North Africa, Japan, Java, and North America. Of the other genera, Calommata inhabits Central and South-East Asia and Japan, Brachybothrium, Atypoides, and Hexura are peculiar to North America, while Mecicobothrium comprises a single species (M. thorelli) native to the Argentine.[[311]]
Fam. 4. Filistatidae.—Cribellate Spiders of moderate size, usually brown or yellow in colour, with smooth integuments and somewhat long tapering legs. The eight eyes are compactly arranged, and the palpal organs of the male are of simple structure. The six spinnerets are short, the anterior pair being thick and separated. Two pulmonary sacs, with two minute tracheal stigmata close behind them and widely separate.
There is but one genus, Filistata, in this family. About fifteen species have been described, five of which inhabit the Mediterranean region. Three are found in America, and others inhabit Central Asia, the Philippines, and Australia. The genus is not represented in this country, but one species, F. testacea, has an extremely wide distribution in the Old World, while F. capitata extends throughout the American continent.
The calamistrum of the female is short, only occupying a portion of the metatarsus of the fourth leg. The cribellum is divided. These spiders weave a web of close texture, of an irregular tubular form.
Fam. 5. Oecobiidae (Urocteidae).—Two very remarkable genera constitute this family, Oecobius and Uroctea.
The species of Oecobius, about fifteen in number, are small spiders, inhabiting sub-tropical countries—and especially desert regions—and spinning a slight web under stones, or in holes in walls. The female possesses a small transverse cribellum, the two halves of which are widely separated. The calamistrum is but feebly developed. No example has occurred in this country, but nine species have been described in the Mediterranean region.
