The Megacorminae include but a single Mexican form, Megacormus granosus. There is a single toothed keel under the “tail,” and all the under surface is spiny. There is a row of long bristles under the tarsus.
In the Euscorpiinae the upper surface of the hand is divided into two surfaces almost at right angles by a strong finger-keel. This is a small group of about six species found in the Mediterranean region. The two genera are Euscorpius and Belisarius.
The Chactinae are without any marked keel on the hand. The scorpions of this sub-family are found in equatorial South America and the West Indies, where there are more than twenty species divided about equally between the four genera Chactas, Broteas, Broteochactas, and Teuthraustes.
Fam. 5. Vejovidae.—No tibial, but two pedal spurs. A single row of hairs or papillae under the tarsus. Sternum generally broader than long. Elongate stigmata, and three lateral eyes.
Seven of the eight genera of this family include only American forms, the principal genus being Vejovis, with about ten species. The genus Scorpiops, however, belongs to the Indian region and numbers more than ten species.[[248]]
Fam. 6. Bothriuridae.—Sternum much reduced and sometimes hardly visible, consisting of two slight, nearly transverse bars.
Of the seven genera of this family one, Cercophonius, is Australian. The other six genera include some dozen South American forms, Bothriurus having four species.
Order II. Pedipalpi.
Arachnids with non-chelate, two-jointed chelicerae, powerful pedipalpi, and four pairs of legs, of which only the last three are ambulatory, the first being used as tactile organs. The cephalothorax is usually covered by an undivided carapace, but the pedunculated abdomen is segmented. Respiration is by lung-books.
The Pedipalpi are a little-known group of animals of nocturnal habits. Though rarely seen they are widely distributed, being found in India, Arabia, the greater part of Africa, and Central and South America. They are of ancient origin, a fossil genus, Graeophonus, of the Tarantulidae (Phrynidae, see p. [312]), occurring in the Carboniferous strata in North America. They live under stones and bark, and in caves, where, when disturbed, they seek safety in crannies in the rock.