718 Bulletin American Museum of Natural History. [Vol. XXIII, 



four longitudinal ridges of which the median pair are blunter and separated by a 

 longitudinal groove deepening suddenly at the posterior margin of the segment to 

 form a somewhat circular pit. Gaster much smaller than the head, fully ^ longer 

 than broad, widest posteriorly, with straight sides and anterior border and acute 

 anterior angles. The first segment has a sharp longitudinal ridge on each side but 

 no median depression. Legs long and rather stout. 



Opaque throughout; mandibles very finely striated; head above irregularly 

 reticulate-rugose, more coarsely behind than in front. Remainder of body and 

 appendages very finely and obscurely punctate-granular and faintly reticulate, 

 except the gaster which is more distinctly and evenly punctate and slightly roughened 

 on its upper surface. Legs and scapes also slightly scabrous. 



Hairs yellowish; very short, curved and sparse, subreclinate, most distinct on 

 the ga ter and appendages. Pubescence very fine, whitish, confined to the antennal 

 funiculi. 



Yellowish ferruginous; upper surface of head and gaster and the ridges and tips 

 of the spines darker. Mandibular teeth black. 



St.. Vincent: Bellisle (H. H. Smith). 



Cuba. 



I have redescribed this species from a type specimen kindly sent me by 

 Professor Forel who has also described a closely related species, M. gaMii, 

 from Brazil. The subgenus Mi/cocepurus, as Forel has shown, is related 

 to the other subgenera of Atta on the one hand and to Cyphomyrmex and 

 Myrmicocrypta on the other. It is peculiar and aberrant, however, in its 

 small size, its small, closely approximated frontal lobes and spinulation. 

 Hitherto M. sviiihi has been known only from St. Vincent. I have received 

 specimens from Cuba. Among the materials in my collection I find also a 

 number of workers from two other localities and representing the following 

 varieties : 



11. Atta (Mycocepurus) smithi var. borinquenensis var. nov. 



Porto Rico: Vega Baja, Arecibo, Utuado, INIonte Mandios (Wheeler). 



The workers of this form resemble the type very closely in size, coloration 

 and sculpture but have on each side of the occipital furrow at the postero- 

 median border of the head, a distinct tooth which is nearly as large as the 

 teeth which form the posterior corners. The posterior epinotal spines are 

 curved inward at their tips as in the type. 



12. Atta (Mycocepurus) smithi var. tolteca var. nov. 



Mexico: Tuxpan, Jalisco (J. F. McClendon). 



Closely resembling the type, but of a yellow color and with straight, 

 more acute and more erect posterior epinotal spines and feebler cephalic 



