THE CAUSE OF MINTETIC nESEMBLANCE. 



589 



sometimes crosses the ceplialothorax, sometimes the abdomen. 

 The absence o£ antennae in the spider is known to be compea- 

 sated in some of the species, which have been studied in the 

 living state, by the habit of holding up one pair of legs, while the 

 walking legs are thus reduced to the ant-like number of six. Of 

 two well-known North A.merican species, Synageles picata holds 

 up the second pair, and Si/nemosyna formica the first. The habits 

 of seizing and dealing with prey, and the movements generally 

 are extremely nn-spider-like and most suggestive of ants ; so 

 that the nervous and muscular systems, as well as the body- 

 form, have been modified. The remarkably ant-like appear- 

 ance of these two species is shown in the adjoining fig. 1 (A 

 and B). 



Fig- 1- Fig. 2. 



Fig. 1. — Two "N'ortb-American Atticl spiders which resemble ants. A is Sijnageles 

 }ncata; B, Syjiemosyna formica. (From Gr. W. and E. Gr. Peckhani, 

 Occasional Papers of the Nat. Hist. Soc. of Wisconsin, vol. i. 1889, 

 pp. 110 & 112.) 



Fig. 2 (X 3). — The youug larva of Siaurojms fagi seen from above and from 

 the left side. 



Among the Insecta, too, there are many examples of an ant-like 

 appearance brought about by changes of the same kind as those 

 mentioned above, although less marked because the forms 

 to be approximated are less essentially different, .limong the 

 Lepidoptera the young larvae of a British moth, Sfauropus fagi^ 

 have often been described as resembling ants. The likeness has 

 recently been analysed in much detail by Portschiuski (" Colo- 

 ration marquante et Taches ocellees," V. : St. Petersburg, 1897, 

 p. 44). This acute observer considers that the head of the 



LINN". JOUEN. — ZOOLOGY, VOL. XXVI. 42 



