Many kinds of monkeys, squirrels, and several sorts of birds, as well as lizards, tortoises, frogs, and toads prey upon spiders. A species of black sheep, found in the steppes of Asiatic Russia, unearths the tarantulas (Lycosa), and eats them. ("Une espèce de brebis noire, dans les steppes de la Russie asiatique, déterre les tarentules et les mange"). In the East India Archipelago there is an entire genus of birds of the passerine order, which have been named "Arachnoptères" because the different species of which it is composed live exclusively on spiders. Besides these, the centipede (_Scolopendra_), and the following Hymenopterous insects, _Philanthes_, _Sphex_, _Pompilus_, _Pimpla Ovivora_, and _P. Arachnitor_ [which last lay their eggs in the eggs of spiders], carry on perpetual hostilities against them. I have seen it stated that ants are among the worst enemies of spiders, driving their galleries through the silk tubes of the latter and devouring their eggs. Of this I have never seen any trace, and, on the contrary, have on four occasions found the remains of ants' bodies at the bottom of the trap-door spiders' nests. I have but seldom detected any refuse in these nests, and this accords with what M. Erber tells us[96] of the care with which _Cteniza Ariana_, which he watched by moonlight in the island of Tinos, carried away the empty bodies of the beetles, the juices of which had been sucked out, to a distance of some feet from its hole. In October, 1872, however, I found a black layer of débris at the bottom of five nests of _Nemesia Eleanora_, and this was composed principally of the remains of insects, and among others of some rather large beetles. [Footnote 96: A translation of these very interesting observations will be found below in Appendix B.] As far as I am aware, M. Erber is the only naturalist who has ever placed any detailed observations on record as to the nocturnal habits of a trap-door spider in its native haunts; and we may learn from him how we should watch these creatures, if we wish to discover the manner in which they take their prey, and of what their prey consists. He relates how he witnessed the capture, in the long low snare which _Cteniza Ariana_ spreads close to the ground, of two strong, night-flying beetles (_Pimelia_ and _Cephalostenus_), and how these were at once devoured, and their horny coats thrown away. More observations of this kind are greatly wanted, as it is most important that we should know what are the principal sources of food upon which these spiders depend for their existence. If we could answer the questions, what do they eat? and what do they fear? we should have advanced a long way towards resolving the larger problem as to the causes which limit particular species to certain districts.