MR. R. I. POCOCK — MIMICRY' IN SPIDERS. 263 



thorax, head, and two eyes of the ant. Thus the posterior end o£ tlie spider 

 corresponds to the anterior end of the ant, an anomaly no doubt connected 

 with the habit, so characteristic of the Thomisidse, of moving sideways and 

 backwards with ahnost greater facility and frequency than forwards. 



A second species of Amycicea — A. lineatipes — has been discovered at 

 Singapore also associated with (Ecophylla smaragdina. It is a much less 

 perfect mimic than A. foi'ticeps because the abdomen is shorter, oval, and not 

 constricted, so that the head and thorax of the insect are much less clearly 

 indicated ^. 



Amongst the Salticidse (Attidse) are found species presenting every grade 

 of ant-mimicry, from forms like Pecklmmia picata which imitates ants in 

 general^ to the numerous species of Myrmarachne, in which, in many cases, 

 the mimicry of particular species of these insects is carried to a state of 

 perfection equal to anything found in the Clubionida^. It is needless to give 

 a complete list of all the genera that furnish illustrations of this phenomenon, 

 since the structural modifications which combine to produce the resemblance 

 are in all essential respects of the same nature in all, and differ in no important 

 respects from those already described in the Glubionidse and other families. 

 An exception to this, however, is furnished by the males of some of the 

 species of Myrmaracline, in which the elongated mandibles share in producing" 

 the required effect. For instance, in M. plataleoides (fig. 4) — a Ceylonese 

 species which, like Amycicea forticeps, mimics and associates with (Ecophylla 

 smaragdina — the mandibles, which are stretched straight forwards in front of 

 the head, are narrow in their proximal half and swollen distally, and are 

 furnished with a pair of black spots said to resemble the eyes of the ant. In 

 this species and many others of the genus, both carapace and abdomen are . 

 constricted and the pedicel is elongated. In others the abdominal con- 

 striction is absent, and the thoracic varies much in depth. The genus 

 Myrmaracline contains some seventy or eighty species, and is distributed over 

 all the warmer temperate and tropical countries of the world. The species 

 vary much in colour to accord with that of the models they live with and 

 copy. A tolerably common Oriental species is M. providens which mimics 

 Sima rufonigra ; another in Venezuela mimics Anochetus emarginatus. 

 Even in England the genus is represented by 31. formicaria, which occurs 

 with species of the genera Myrmica and Formica f. Of the remaining 

 genera the following may be mentioned : — Bocus from the Philippines, 

 differing only from Myrmaracline in the method of constriction of the 

 sternum, which is expanded between the coxse of the first and second legs 

 instead of between those of the second and third pairs ; the Neotropical 

 Sarinda, Erica, and Fluda, which have the constriction of the carapace some- 



* 0. P. Cambridge, P. Z. S. 1901, p. 14, pi. 6. fig. 4; also Shelford, P. Z. S. 1902, p. 266. 

 t H. Douistliorpe, ' The Zoologist,' 1908, p. 424. 



