726 MB. B. I. POCOCK ON ETHIOPIAN SPiDEEs. [June 15, 



So far as the habits of these families are known they afford 

 some clue to the structural differences. The Cteuizidae and 

 Migidae, 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, aud chipping off pieces of lichen 

 or bark wherewith to conceal the silk. The Dipluridse, on the con- 

 trary, spin snares in the form of horizontal sheets of webbing, which 

 lead a^ 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 Baiychelidae 

 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 uever closed by a door ; 

 while others of this section live in trees, spinning a silken 

 domicile in the hollow trunks, in forked branches, or in rolled 

 leaves, 



Family Ctbnizid.5E, Thorell. 



Ctenizoidce, 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 n]argin 

 and opposite the coxa; of the 3rd pair of legs. — 

 (Subfam. Otenizin.b.) 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 ] st 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 Actinopus from the Neoti'opical 

 Eegion and Eriodon from Australia. In my opinion there is 

 very little evidence tkat the three are related. In the first place, 

 Stasimopus does not possess the square maxilla foitnd in the other 

 two, this segment being no wider than the other coxaj and nearly 

 twice as long as wide, though it possesses a longer distal process 



