The other two families of this Sub-order—Fam. 2, Cosmetidae; Fam. 3, Gonyleptidae—include a large number of species, some of considerable size (up to an inch in length of body), found in Central and South America.
Sub-Order 3. Plagiostethi.[[347]]
(PALPATORES.)
First abdominal segment produced forward ventrally to the level of the first pair of legs, bringing the mouth and the genital opening very near together. Sternum consequently much reduced. Pedipalpi thin, with terminal claw absent or rudimentary. Terminal claws of the legs single.
The Plagiostethi include most of the Harvestmen of temperate regions, the most familiar examples of these creatures belonging to the large family Phalangidae, and being much more in evidence than the slow-moving and ground-living forms included in the other families.
Fam. 1. Phalangiidae.—Eye-turret always far removed from anterior border of cephalothorax. Second pair of legs with well-marked maxillary lobes. Legs similar, without the false joint called “trochantin.” Multiarticulate tarsi. Simple pedipalpi, with tarsus much longer than tibia, and possessing terminal claw. Some have soft, some coriaceous integuments.
The Phalangidae fall naturally into two groups or sub-families, named by Simon Sclerosomatinae and Phalangiinae. The first group consists of more or less coriaceous forms living among moss and herbage. They are not very numerous, there being only about twelve known European species divided among the three genera, Sclerosoma, Mastobunus, and Astrobunus.
Fig. [235].—Sclerosoma quadridentatum. (After Pickard-Cambridge.)
Two species of Sclerosoma are found in England, S. quadridentatum occurring not uncommonly among moss or under stones in various parts of the country. Its back is studded with wart-like tubercles, which give it a characteristic appearance.
The Phalangiinae are soft-bodied Harvestmen, always with long legs, which in the genus Liobunum attain an inordinate length. There are nine European genera, Liobunum, Prosalpia, Gyas, Oligolophus, Acantholophus, Phalangium, Dasylobus, Platybunus, and Megabunus, comprising in all about fifty species. Five of these genera are represented in England.