6 Psyche [March- June 
behind as in obscurior. The tubercles on petiole and postpetiole 
larger and more spine-like than in obscurior. 
Lateral ridges and longitudinal depressions on first segment of 
gaster indistinct or absent. 
Mandibles striate and rather shining. All other regions opaque, 
densely and finely punctate, giving a granular appearance. Tu- 
bercles and hooked hairs moderately numerous, about as in 
obscurior. The thoracic spines are abundantly covered with hairs 
and tubercles. No tubercles on legs, scapes, pronotum anterior 
to the spines, most pleural regions of the thorax, and venters of 
pedicel and gaster, although these parts have numerous hooked 
hairs. Tubercles larger on occipital lobes than on other parts of 
head; tubercles on vertex and hind portions of antennal scrobes 
often prolonged into small longitudinal ridges, or connected by 
ridges to form small longitudinal carinulae. No pubescence except 
on funiculi. 
Color entirely black except for the mandibles, tarsi, and articu- 
lations of femora and tibiae, which are brown. 
Male and female unknown. 
Described from 59 specimens collected November 5 and No- 
vember 8, 1942, from the same nest in the desert near La Rosa, in 
the state of Coahuila, Mexico (Elinor Buren, collector) . Holotype 
in the author’s collection; paratypes in the author’s collection 
and in the National Museum. The nest was of a simple crater 
type unlike that of turrifex or septentrionalis. The ants were ex- 
tremely slow and sedate in movement even in hot sunlight. They 
were observed bringing in small green bits which seemed to be 
pieces of grass. The hard soil prevented excavation. 
T. smithi seems most closely related to T. septentrionalis ob- 
scurior Wheeler but the black color, broader, more robust head 
and thorax, differently shaped thoracic spines, weaker frontal 
carinae, etc., seem sufficient distinctive characters. 
This species is not closely related to turrifex which also occurs 
in northern Mexico (Vallecillo, Nuevo Leon). T. turrifex has 
shorter antennae, a different color, narrower head, differently 
shaped frontal and genal carinae, tubercles on legs and scapes, etc. 
T. jamaicensis and its variants often approach or are similar in 
color to smithi , but these forms may be easily distinguished by 
the three prominent spines or large tubercles on each occipital 
lobe, the differently shaped head, eyes, thoracic spines, etc. 
T. saussurei, arizonensis, and desertorum may all be distin- 
