SPIDERS MIMICKING ANTS 253 



of body is often made to assume the appearance of an 

 ant, with its three-fold division, by a constriction which 

 sometimes crosses the cephalothorax, sometimes the 

 abdomen. The absence of antennae in the spider is 

 known to be compensated 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- American species, Synageles picata holds up 

 the second pair, and Synemosyna formica the first. The 

 habits of seizing and dealing with prey, and the move- 



FIG. 2. 



FIG. i. Two North- American Attid spiders which resemble ants. A is Synageles 

 pi(ata\ B, Synemosyna formica. (From G. W. and E. G. Peckham, 

 Occasional Papers of the Nat. Hist. Soc. of Wisconsin, vol. i, 1889. pp. no & 



112.) 



FIG. 2 (x 3). The young larva of Stauropus fagi seen from above and from the lelt 

 side. 



ments generally are extremely un-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 appearance of these two species 

 is shown in the adjoining Fig. i (A and B). 



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. Among the Lepidoptera the young larvae of 

 a British moth, Stauropus fagi, the ' Lobster', have often 

 been described as resembling ants. The likeness has 



