THE DEGENERATE SLAVE-MAKERS. 



489 



all the other social parasites in lacking the worker caste. The ants of 

 both groups are throughout life dependent on their hosts and are, there- 

 fore, permanent social parasites, but I would restrict this term to the 

 workerless species, since they represent the most extreme type. 



A. The Degenerate Slave-makers. This group embraces only 

 two genera, Strongylognathns and Harpagoxenus, formerly known as 

 Tomognathus. Strongylognathns is a strictly palearctic genus, con- 

 fined, so far as known, to Europe, western Siberia, Asia Minor and 

 the southern shores of the Mediterranean. It contains only two spe- 

 cies, testaceus and huberi, but the latter has several subspecies and 

 varieties (christophi, rehbinderi, afcr and c a cilice). These ants are 

 very small, measuring only 2.5-4.5 mm. in length, and of a yellowish 

 or dark brown color. The head of the worker and female is more or 

 less excised behind, with very prominent posterior corners and sub- 

 parallel sides. The mandibles are toothless, narrow, pointed and 

 sickle-shaped, like those of Polyergus, but without denticles. All of 

 the forms occur only in nests of Tetramorium cespitum (Fig. 273, of), 

 a very common ant which they closely resemble in size and appear- 

 ance. 



i. Strongylognathns huberi (Fig. 273, c). This species was origi- 



FIG. 273. a, Strongylognathns testaceus worker. (Original.) b, head of female 

 of same ; c, S. huberi, head of worker ; d, Tetramorium cespitum L. host of 5". tes- 

 taceus and liuberi. 



nally described by Forel (1874) from specimens taken in Canton 

 Vallais, Switzerland, on a warm slope near Fully, in the valley of 

 the Rhone. More recently (iqood) he has published additional obser- 

 vations on a colony from the same locality. He found that the workers 

 of huberi are very numerous, that they will go forth in a closed 

 phalanx, much like that of the amazons, and pierce the heads of 

 strange Tetramorium workers placed near their nests and that they 



