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Show 726 MR. R. I. POCOCK ON ETHIOPIAN SPIDERS. [June 15, So far as the habits of these families are known they afford some clue to the structural differences. The Ctenizidse and Migidse, belonging to the group of Trap-door Spiders, are of heavy build and adapted to a sedentary life; but while the former dig their burrows in the ground and are furnished in consequence with the armature of spines on the mandible, known as the rastellum, the latter spin their tubes on the trunks of trees, taking advantage of some suitable depression in the bark, or, with their strong mandibular fangs, biting away roughnesses and inequalities to form a level surface, and chipping off pieces of lichen or bark wherewith to conceal the silk. The Dipluridse, on the contrary, spin snares in the form of horizontal sheets of webbing, which lead at one extremity into a silken tubular retreat; and since the livelihood of these species depends upon the agility with which they dart upon insects that fall upon the web, their light build and long slender legs become at once intelligible. The Barychelidae live in burrows in the ground, and some of them make trap-doors like those formed by the Ctenizidae. Many of the Theraphosidse too dig tubes in the soil, but the tube is never closed by a door; while others of this section live in trees, spinning a silken domicile in tbe hollow trunks, in forked branches, or in rolled leaves. Family CTENIZID.E, Thorell. Ctenizoldce, Thorell, Ann. Mus. Genova, xxviii. p. 394, 1889- 1890 (-Diplura, &c). The known African genera of this family may be distinguished as follows :- a. Eyes forming a single cluster on the fore part of the head, being arranged in two transverse lines ; maxilla (basal segment of palp) furnished with a longer process at its distal end, only armed with a few basal teeth ; sternum with a pair of sigilla (scars) remote from the margin and opposite the coxa? of the 3rd pair of legs.- (Subfam. CTENIZIM:.) Stasimopus. b. Eyes forming two clusters, a pair situated close together in the middle line upon the border of the carapace ; the remaining six some distance behind; maxilla with a smaller distal expansion, toothed all along the anterior edge ; sternum with two pairs of sigilla close to the margin and opposite the bases of the 1st and 2nd legs.- (Subfam. IDIOPIN.E.) a'. Tibia of 3rd leg not excavated above at the base Acanthodon. b'. Tibia of 3rd leg distinctly excavated above at the base. Heligmomerus. Mons. Simon refers Stasimopus to a subfamily, the Actinopodinse, which contains in addition the genus Actlnopus from the Neotropical Begion and Eriodon. from Australia. In m y opinion there is very little evidence that the three are related. In the first place, Stasimopus does not possess the square maxilla found in the other two, this segment being no wider than the other coxae and nearly twice as long as wide, though it possesses a longer distal process |