Fam. 29. Platoridae.—The Platoridae are Thomisid-like, medium-sized spiders, generally with a uniform yellow or brown coloration. The spinnerets are their most characteristic features. The median pair present a large flat surface studded with two parallel rows of large fusulae, while the anterior pair are situated outside them, and are thus widely separated. There are only three genera, and very few species of this family. Plator insolens is a Chinese species. Doliomalus and Vectius belong to South America.
Fam. 30. Agelenidae.—Sedentary spiders with slight sexual dimorphism; with three tarsal claws and devoid of scopulae.
The Agelenidae spin a more or less extensive web of fine texture, usually accompanied by a tubular retreat. Our commonest cellar spiders belong to this group, which may be divided into three sub-families, Cybaeinae, Ageleninae, and Hahniinae.
(i.) The Cybaeinae include some sixteen genera, of which two deserve special mention on account of the peculiar habits of the spiders belonging to them.
Desis is a genus of marine spiders, said to live on coral reefs below high-water mark, and to remain in holes in the rock during high tide, enclosed in cocoons impermeable to the sea-water. At low tide it is stated that they come forth and prey upon small crustaceans. Argyroneta has only one species, A. aquatica, spread throughout Europe and North and Central Asia. It is the well-known “Water-spider,” which is so often an object of interest in aquaria.
(ii.) The Ageleninae also contain sixteen genera, but it is a much larger group, some of the genera being rich in species. They are mostly moderate or large-sized hairy spiders, living in temperate or cold climates. There are about fifty species of Tegenaria, seven of which have been recorded as British.
Our commonest Cellar-spider is T. derhamii, but the very large long-legged species found in houses in the southern counties of England is T. parietina (= guyonii = domestica). There are not many species of Agelena, but one, A. labyrinthica, is a common object in this country, with its large, close-textured web and accompanying tube spread on grassy banks by the wayside. Coelotes atropos is a formidable-looking spider, found occasionally under stones in England and Wales. Another genus, Cryphoeca, has three British representatives.
(iii.) The Hahniinae are recognised at once by their spinnerets, which are arranged in a single transverse line, the posterior pair being on the outside, and generally much the longest. Hahnia contains several species of very small spiders, of which four or five are British, usually occurring among moss or herbage. The aberrant form Nicodamus (Centropelma), usually placed among the Theridiidae, is removed by Simon to the Agelenidae, forming by itself the sub-family (iv.) Nicodaminae.
Fam. 31. Pisauridae.—The Pisauridae are hairy, long-legged spiders, intermediate, both in structure and in habits, between the Agelenidae and the Lycosidae. Many new genera have recently been added to the group, but many of them only include one or two species.
Pisaura is spread throughout the temperate regions of the Old World, and P. (Ocyale) mirabilis is common in England, being found abundantly in woods and on commons. It is a striking spider, more than half an inch in length, and its elongate abdomen is marked on either side with a sinuous longitudinal white band.