The spiders of the genus Micrathena (Acrosoma) have a more elongate cephalothorax, and sometimes the spines are exceedingly long, far exceeding the length of the body proper. Among the less spiny members of this group are some remarkable mimetic ant-like forms.
(vii.) The Poltyinae include some remarkable spiders, found in Africa and South Asia for the most part, though sparingly represented in America and Oceania. They are generally largish spiders, often with a very odd conformation of the abdomen, which is generally much raised. The type genus is Poltys.
(viii.) The Arcyinae, which are more characteristic of Australia and the neighbouring islands, are a small group of spiders, usually yellow with black markings, and with the somewhat square-shaped cephalothorax usually prominent at the angles. The type genus is Arcys.
Fam. 24. Uloboridae.—The Uloboridae are cribellate spiders, with rather elongate cephalothorax, devoid of median fovea. The cribellum is transverse and generally undivided. The first pair of legs are usually much the longest. The metatarsi of the fourth legs, in addition to the calamistrum, bear a number of generally regularly arranged spines. The eyes are often situated on tubercles. Three sub-families are recognised, Dinopinae, Uloborinae, and Miagrammopinae.
(i.) The Dinopinae are a small group comprising only two genera, Dinopis and Menneus. The calamistrum is short, occupying not more than half of the metatarsus. Twenty species of Dinopis and six of Menneus are scattered over the tropical regions of the world.
(ii.) The Uloborinae include a number of spiders which have been described under several generic names, but are now considered to fall into two genera, Sybota and Uloborus. Sybota has only two species, one in the Mediterranean region and one in Chili. There are about sixty species of Uloborus, some of which have a wide distribution, while many (e.g. U. republicanus, of Venezuela) are social. The type species, U. walckenaerius, is a very rare spider in England.
(iii.) The Miagrammopinae include two genera containing some very interesting forms. The genus Miagrammopes, of which twenty species have been described, though the number is probably far greater, is characterised by a very long cylindrical abdomen, and by the apparent possession of only four eyes, in a transverse row. These are really the posterior eyes; and the anterior eyes, or some of them, are present in a very reduced condition. Little is known of the habits of these spiders.
Fig. [212].—Hyptiotes paradoxus, ♀.
The other genus, Hyptiotes, though only boasting three species, possesses a special interest on account of the remarkable snare constructed by the spiders which belong to it. This has already been described in the section upon defective orb-webs (see p. [349]).