The Holosomata and Rhynchostomi are probably offshoots from the stem of the Araneae, and it is not unlikely (in view of the structure of the prosomatic somites of the Tartarides) that the Solifugae are connected in origin with the Pedipalpi.
P., "' A New Family (Tartarides) and Genus of Thelyphonidea," Ann.
Iv., 1899 Thorell, " Tartarides, &c."
A third division, the Tartarides, a subordinate group of the Uropygi, contains minute Arachnida differing principally from the typical Uropygi in having the caudal process unjointed and short.
Apart from the Tartarides, the Pedipalpi are large or medium-sized Arachnida, nocturnal in habits and spending the day under stones, logs of wood or loosened bark.