/.V JAVA. 



119 



XI, Oun tmv Gcnm of Spiders. ByKcv. 0. P. Cajibbidge, i[.A.,C3LZ.S.,&e. 



(Extracted from ne Proc. Zool. Soc.. 1884, p. 196 ei s«qq.) 



Mr. H. 0. Forties lias lately desorilxid (Pm<:ee'tinffs of the Zoo^wjicttl 

 Stjckhi, 1883, p. 580,) utider tho provirtionul nanio of Thommts tkripmis, 

 the h/ibits o( u which ho met witb in Java, The spider itself is 



reiuarkftbio from iU exact re^emhlauco to the droppings of a bird; and it 

 18 still more remArkablo from the increased resembtaEce added in tho 

 spinning of a thin wliite wab ou the RUrfiaoe of a leaf, by meaas of which 

 ifc seottres it6Qif,ou its back, to the leaif, leaving its [egs free to enclave and 

 seize any insect nnwittiugly resting npon or crossing the apparantly 

 innocnoas bird-dropping. Jlr. ForliHsy kindly sent mo tiie spider for 

 examination l>efore writing an account of its liabits. I immediat<j|y 

 recognised its near affinity to ati Eiist-Indian spider {ThnntmiH tiil)^:trmi!>\ 

 BL), of which I ijosse^ the tj'jx) spcimen ; but, nnablo at the moment to 

 make a tkorongh examination ana scareh throngh books and speciraous, 

 coujucturcd that it was allitxl to some spiders descriljod by Dr. Karsch, 

 and to one sent me some years ago from Sontb Africa- A more completo 

 examination ainco made hiw convinced me that these latter spociea 

 (referred to by Sfr. Forbo.s) IjoIodct to entirely different groaps. I find, 

 however, in my coiJoction two otiier spiders, from Ceylon and Bombay, 

 of the same genu*! and very closely allied in species, but quite distinct 

 from that wtiich Mr. Forbtw notes. Upon these, to^jether with the one 

 last mentioned and T/iommis tidi^rosm,, Bl., I have ventnrcd to found a 

 new genus, and I beg to record my thanks to its disoovei-cr for so kindly 

 sendkig me an exam^ple of Tfumn'sim 'lecipi't'm and for hanng also made 

 known to ns the very jieculiar and interesting habits lielonging, not only 

 to that spider, but also, I have little donbt, to other closely allied 

 species.* 



In bis deseription of tbe habits of T, dficfpicns, ilr. Forbes expresses 

 tho difficulty he has in iiuderstaiiding the formation by the spider of a 

 web which, while serving to attach itself to the leaf, at the same time m 

 exactly represents the fluid ix>rtiou of abird's-tlropping spread out on the 

 leaf around the more solid parts ; and his conclading sentenoea seem to 

 me to imply the conclusion that the spider consciously sujiplenients the 

 effects of natural selection on its form and resemblance to the solid ex- 

 creta, by spinning a web to resemble the fluid portion. It seems, to me, 

 on the contrary^ tiiat the whole is easily explaine*! by the operation of 

 natural selection, witljout supposing conscioitsness in the spider in any 

 part of tlio process. The web spun on the surface of the leaf is evidently, 

 so far as tho spider has any design or consciousness in the matter, spun 

 simply to Bocure itself in the proper position to await and seize its prey. 

 The silk, which by its tineness, whiteness, and close adhesion to the leaf 

 causes it to resemble the more fluid parts of the excreta, would gradually 

 attam those qualities by natural selection^ just as the spider it-self would 

 gradually^ and probably /^tr/ jm^su, lKM?ome, under tho influence of the 

 same law, more and more like the solid portion. 



• DoIeschdS ('Twecde Bijdrage tot de Kennis der Arfu-huidou van den In- 

 dirfheri Arctiijxil,' p. 5S, p!. xi. U and Oa) descirlbod atul figures, also from Jiiva, 

 a epiiltjf {Tfwutigwt di**tnnli«, Iki].) jHWiiibly of tlibt gt'tiud, ntid perhiipi nearly 

 alliuJ tn T.dtcipifnt; but tho ik'4?cription is tofj meiigro and genfcni] to enable 

 any wrlAhi concluaioa to be drawn from it, and the li^iu-e given of the eyes is 

 tytully urdike. 



