MR. R. I. POCOCK — MIMICRY IN SPIDERS. 269 



Prof. Poulton * long ago suggested that the larvce of two British species o£ 

 Hawk-Moths (CJioerocampa elpenor a.nd porcellus) are protected by the likeness 

 to the heads of snakes presented by their anterior extremities which are 

 ornamented with large eye-like spots. The correctness o£ this sm'mise has 

 been subsequently substantiated in the case of these two species by Weismann 

 and Lady Verney, and the interpretation has been extended to other species 

 of the genus Chcerocampa, namely, to C. osiris by Mr. Gruy Marshall f in 

 S. Africa, and to C. myodon by Mr. Shelford % hi Borneo. The experimental 

 proof of the truth of Prof. Poujton's view justifies the acceptance as a working 

 hypothesis of the suggestion put forward by Mr. Saville Kent § that the 

 Australian Argyopid, Pcecilopacliys bispinosa, is protected from attack by the 

 similarity its abdomen presents to a reptile's head. The cephalothorax of this 

 spider is sm.all ; but the abdomen is of large size, wide, subtriangular in form, 

 broad in front, gradually narrowed behind and flattened above. Its integu- 

 ment is a delicate mottled lilac hue, with a pair of pale yellow circular eye- 

 like prominences, set one on each side of the broad anterior part of its upper 

 surface. These in conjunction with the flattened sub triangular-shaped 

 abdomen impart to this region, according to the observer, a singular similarity 

 to the head of a small snake or goggle-eyed, gecko-like lizard. Lurking at 

 the bottom of its silken tube with nothing but its abdomen visible, this spider 

 suggests to a prospective enemy that it is trespassing upon the home of a 

 reptile and running the risk of being itself destroyed. A similar appearance 

 may be seen in a few other spiders of this family ; in Cyrtaracline lactea from 

 East Africa for example ||. 



Mr. Saville Kent^s ingenious suggestion is worth recording so that it may 

 hereafter be refuted or substantiated by experiment. 



In all the cases of mimicry real or imaginary hitherto considered, the 

 resemblance to the model appeals to the enemies' sense of sight. In one 

 possible case amongst spiders the appeal is made to the auditory sense. In 

 South Africa there is a fairly large spider, Sicarius, belonging to the 

 Scytodidse, which is furnished with a stridulating organ consisting of a 

 series of short thick spines on the inner surface of the femur of the palp and 

 of a finely-ridged area on the adjacent outer surface of the mandible. A 

 species found by Simon in the Transvaal lives under stones, lying flattened 

 with legs extended upon the soil. Its movements are extremely slow ; and 

 instead of attempting to escape when seized, it lies still and stridulates, giving 

 out a sound resembling the buzzing of a bee. The behaviour of this spider 



* 'Colours of Animals,' p. 261; see also 'Essays on Evolution,' pp. 367-368, 1908. 



t Trans. P]nt. Soc. London, 1902, p. 397. 



% Proc. Zool, Soc. 1902, pt. ii. p. 253. 



§ ' Naturalist in Australia,' p. 267, 1897. 



II Pocock, Ann. Mag. Nat. Hist. (7) ii. p. 446, 1898. 



