We may consider certain genera as typical of the various groups into which this sub-family naturally falls. Theridion is the richest genus of the entire order, numbering some 320 species, of which seventeen inhabit the British Isles. During the summer months nearly every bush is studded with the irregular webs of these little spiders, generally prettily coloured, and with globular abdomen. The commonest is T. sisyphium, which swarms on hollies and other bushes all over the country. One of the handsomest is T. formosum, a rather local species, about a sixth of an inch in length, with the abdomen beautifully marked with oblique lines of white, yellow, red, and black. T. tepidariorum, common in conservatories, is like a large and plainer edition of T. formosum. T. riparium is remarkable for the curious earth-encrusted tube which it forms for the reception of its egg-cocoon. T. bimaculatum may often be seen among coarse herbage, holding on to its ridiculously large egg-cocoon; it is a small spider, and the sexes are more than usually unlike.
Latrodectus and Dipoena are associated exotic genera, including some of the largest species of the group. Latrodectus is peculiarly interesting on account of the great reputation for especially poisonous properties which some of its species have acquired. The New Zealand “Katipo” is L. scelio, while L. 13–guttatus enjoys an almost equally evil reputation as the “malmignatte” in Corsica. The American species L. mactans (Fig. [197], p. 362) is also considered highly venomous. These spiders form their irregular webs on low bushes, and it is curious that they are usually marked with red or yellow spots on the abdomen. They have been referred to in the section on the venom of spiders (see p. [362]).
The genus Steatoda possesses one English species (S. bipunctata) which is extremely common in buildings and in the angles of walls, and is a rather striking spider, with dark cephalothorax, and livid brown abdomen with a broken white stripe down the middle. Several closely allied genera are also sparingly represented in this country, among which may be mentioned Crustulina (two species), Asagena (one species), Teutana (two species), Lithyphantes (one species), Laseola (five species), and Euryopis (two species). In some of these the male is provided with a stridulating organ between the thorax and abdomen (Fig. [183], p. 327). The remarkable genus Tetrablemma (see p. [318]) is considered by Simon to have affinities with this group, though Pickard-Cambridge, who first described it, is inclined to rank it among the Dysderidae.
Fig. [208].—Trithena tricuspidata ♀. × 3½. (After Simon.)
(iv.) The Phoroncidiinae are a remarkable group of spiny Theridiids whose superficial resemblance to the Gasteracanthinae of the Epeiridae (see p. [409]) has often deceived Arachnologists as to their true affinities. There are eight genera, all exotic, inhabiting hot countries, and spinning a Theridion-like web on bushes. Phoroncidia has twelve species in South Asia and Madagascar. Trithena (Fig. [208]) is its American representative, five species being found in South America. Ulesanis has about twenty species, and extends from South America to Australia.
(v.) The Erigoninae are an immense group of minute, sober-coloured spiders, which include the “Money-spinners” of popular nomenclature, and are largely responsible for the gossamer which fills the air and covers every tuft of grass in the autumn. The number of species described is very large and constantly increasing, and more than a hundred are recognised as British.
Desperate efforts have been made of late years to grapple with this almost unmanageable group, but the multitude of genera which have been proposed can hardly as yet be considered to be finally established. The small size of these spiders, which renders the aid of a microscope necessary to make out their structural peculiarities, robs them of their attractiveness to any but the ardent Arachnologist, but they number among them some of our most remarkable English forms, and many of them well repay examination. The smallest English species, Panamomops diceros, measures about 1 mm. (about ¹⁄₂₅ inch) in length. Many of the groups are jet black, some with dull and others with shiny integuments. They are never greatly variegated in hue, but the glossy black of the cephalothorax, combined with red-brown or yellow legs, gives to some species a rather rich coloration.
Fig. [209].—Profile of cephalothorax of 1, Lophocarenum insanum; 2, Dactylopisthes digiticeps; 3, Walckenaera acuminata (+ abdomen); 4, Diplocephalus bicephalus; 5, Metopobractus rayi.