September, 1902] 



PSYCHE. 



389 



and meso- and metapleiirae. Petiole, post- 

 petiole and gaster shining, covered with 

 delicate, even, microscopic reticulation. 

 Upper surface of petiolar node with a few 

 faint longitudinal rugae. Coxae faintly 

 rugose and, like the remainder of tli.e legs, 

 covered with delicate micro-scopic reticula- 

 tion. 



Body and appendages beset with bri.stly, 

 pale yellow hairs, very long and projecting 

 forward on the clypeus, shorter and erect 

 on the upper surface of the head and thorax, 

 suberect on the remainder of the body. 

 Beard of long, recurved hairs on the lower 

 surface of the head and mandibles well devel- 

 oped. Pubescence none. 



Whole ant deep ferruginous red, excepting 

 the following portions which are black: 

 dentate edges of mandibles, anterior border 

 of clypeus, eyes, ventral edges of the pleurae 

 and sutures between the petiole and post- 

 petiole and between the latter and the gaster. 



Described from numerous specimens 

 collected in the open spaces among the 

 dry chapparal and mesquite thickets 

 near San Pedro Springs, San Antonio, 

 Texas, on the anniversary of the battle 

 of San Jacinto (April 21, 1902). 



P. sancii-hyacinthi superficially re- 

 sembles P. barbatus var. molefaciens 

 Buckley but besides its somewhat smaller 

 size the new species may be very readily 

 distinguished by its very deeply excised 

 clypeus, the straight occipital border, 

 the smooth and shining posterior angles 

 of the head,* the absence of the epinotal 

 spines, the smooth petiole and post- 

 petiole, the much more depressed and 

 rounded petiolar node and obsolescent 



•The last character is sometimes, though rarely, 

 found in harbaiits. 



ventral tooth, and the conspicuously 

 smaller ventral protuberance of the post- 

 petiole. It differs from P. caHfornicus 

 in its larger size, deeper coloring, the 

 extent of the clypeal excision, smooth 

 posterior angles oLHie head and blunter 

 petiolar node, v 



Although it is very easy at first sight 

 to confound P. sancfi-liyaciiithi \i\i\\ P. 

 mo/t'facicits, which occurs in the same 

 locality, this is not the case with tlie 

 nests of the two species. Instead of 

 huge gravel cones or extensive discs, the 

 former species builds only small. Hat, 

 dirt-cones, sometimes in close clusters of 

 two, three or four, and each measuring 

 not more than 4-8 inches across, with a 

 central perforation about \ inch in diam- 

 eter. The periphery of eacli mound is 

 often covered with a thick layer of chaff 

 and other vegetable debris which has 

 been cast away by the ants and may be- 

 come the abode of colonies of termites. 

 The nests are much less populous than 

 those of P. molefaciens. 



PoGONOMYRMEX BARBATUS F. Smith 



var. NiGRESCENS, var. nov. 



The worker of this striking variety 

 differs from the typical barbatus of 

 Mexico in its smaller size and the deep 

 reddish black coloration, not only of the 

 head and thorax as in the Mexican form, 

 but also of the antennal scape, petiole, 

 postpetiole, gaster and femora. The 

 tip of the gaster is very nearly as dark 

 as the base. Mandibles, funiculus, tibiae, 

 tarsi and peduncle of petiole deep fer- 

 ruginous red. Sculpture like that of the 



