Belt considers that the advantages gained by ant-mimicking Central American spiders lies entirely on the side of protection.  In relation to this subject he says:  “Ant-like spiders have been noticed throughout tropical America and also in Africa.  The use that the deceptive resemblance is to them has been explained to be the facility it affords them for approaching ants on which they prey.  I am convinced that this explanation is incorrect, so far as the Central American species are concerned.  Ants, and especially the stinging species are, so far as my experience goes, not preyed upon by any other insects.  No disguise need be adopted to approach them, as they are so bold that they are more likely to attack a spider than a spider them.  Neither have they wings to escape by flying, and generally go in large bodies easily found and approached.  The use is, I doubt not, the protection the disguise affords against small insectivorous birds.  I have found the crops of some humming-birds full of small, soft-bodied spiders, and many other birds feed on them.  Stinging-ants, like bees and wasps, are closely resembled by a host of other insects; indeed, whenever I found any insect provided with special means of defence I looked for imitative forms, and was never disappointed in finding them.”

The ant-like species are probably protected by their appearance from the attacks of many of the larger spiders.  We have kept great numbers of Attidae in captivity, and, although they devoured flies, gnats, larvae, and other spiders, they would never touch ants.  Among spiders, however, as among birds, we find that certain groups subsist almost entirely upon ants.

The class of spiders whose mimicry protects them from their enemies, whether they are birds or other spiders, probably includes at least two of our own ant-like species, Synageles picata and Synemosyna formica, which, in confinement, are always hungry for gnats, but will not touch ants, even of small size.

The existence of a class of spiders which mimic the particular species of ants upon which they prey is not to be questioned, but it is doubtful whether the benefit to the spider is increased facility in capturing the ant, or whether it is merely protective.  It may be that the spider, by virtue of its resemblance to the ant, not only gets an abundant supply of food, but also escapes being eaten itself, and thus enjoys a double advantage.  Both Bates and Wallace take the ground that the advantage derived by the spider consists in greater ease in the capture of prey, but both of these writers refer to spiders only incidentally to illustrate a general proposition, without special consideration of their peculiar conditions.

Mr. Herbert Smith, who has paid a good deal of attention to this subject, is inclined to believe that the mimicry in question is entirely protective.  He writes as follows:—­