230 AMERICAN SPIDERS 



some of the wingless mutillid wasps. And smallest of all are the 

 exceedingly active species of Micaria, clothed with brilliant scales, 

 and the gray, red, and black species of Scotinella that run with great 

 speed. 



In this series of ground hunters are some that compare with the 

 best of the ant mimics, and still others that have become intimately 

 associated with ants and live in their nests. Whereas the jumping 

 spiders are keen-sighted, diurnal types whose mimicry is influenced 

 by reliance on sight, the short-sighted, chiefly nocturnal clubionids 

 have developed in a different pattern. Some emulate the jumping 

 spiders by running about during the day even in the hottest sun- 

 in open places, frequently in company with ants whom they re- 

 semble in size and color. Many exotic types are almost exact phys- 

 ical mimics. Our numerous species of Micaria, as well as the smaller 

 forms of Castianeira, are sun spiders. Their slender golden or black 

 bodies, constricted or crossed with white bars, are covered with 

 flattened and iridescent or brightly colored scales. Moving actively 

 about with quivering front legs, these beautiful vagrants are less 

 susceptible to attack than are other species, and are actually shunned 

 by certain insect and spider predators in the same way as are true 

 ants. 



A similar immunity is probably enjoyed by the many antlike 

 species of Scotinella (or Phrurolithus). Although not diurnal, they 

 are often found associated with ants in the soil debris, and occa- 

 sionally are seen running with them during the day. A few live as 

 myrmecophiles in close association with or even in the interior of 

 the ant nest itself. While little can be said of their life underground, 

 they seem to be tolerated by the ants, and it is known that they feed 

 upon ant pupae and small insects living in the nest. Doubtless they 

 live in comparative safety in their little silken cells, in this way 

 isolated from the ant colony even when in its midst. These myrme- 

 cophiles agree in appearance and color with the particular ant in 

 whose nest they live. Scotinella formica, a black spider with a 

 shining sclerotized plate on the abdomen, frequently is found in the 

 nests of the black ant, Cremastogaster lineolata. The rare Scotinella. 

 britcheri, a yellowish spider, lives with yellow ants, and shows the 

 effects of its cave existence by lacking much of the normal pig- 

 mentation around the eyes. 



Before leaving this series of tramps and vagrants, mention should 

 be made of some close relatives of the Clubionidae. The wanderers 

 of the family Ctenidae (Plate XXXI) are giants that climb over 

 foliage at night or run over the detritus on the soil. Some resemble 



