WHEELER, NORTH AMERICAN ANTS 351 



three minor workers collected by Mr. J. F. McClendon at Guadalajara, 

 Mexico. 



This species seems to be very closely related to C. frontalis Pergande 

 from Tepic, Mexico, but it is decidedly smaller, the clypeus is much 

 broader and more rounded in front, the scapes have no erect hairs and 

 the gaster lacks bluish reflections. Pergande gives no description of the 

 thoracic structure. Another allied Mexican species is C. andrei Forel, 

 but this has a more nearly rectangular clypeus, the head is not obliquely 

 truncated in front and is neither rugose nor red in this region. C. hruesi 

 shows an unmistakable approach to the species of the subgenus Colobopsis 

 through forms like C. abscisus Forel of Guatemala and C. ulcerosus 

 described below. 



YII. Ulcerosus Group 

 S3. Camponotus ulcerosus sp. nov. 



Worker major. Length, 6..5 mm. 



Head rather large, subrectangular, a little longer than broad, as broad in 

 front as behind, with nearly straight posterior and very feebly concave, sub- 

 parallel lateral borders; posterior corners rather angular, anterior corners 

 produced forward as rounded lobes beyond the anterior border of the clypeus 

 and the closed mandibles. In profile the head is high and convex behind, 

 obliquely truncated in front, with flattened gula. The truncated surface is 

 bordei'ed on each side by a coarsely crenate ridge, which runs from the outer 

 edge of the lobe-like anterior corner to a little in front of the eye, where it 

 turns inward and subsides before reaching the frontal carina. This ridge 

 forms the outer boundary of an elongated, irregular and rather deep impres- 

 sion resembling the scar of an ulcer. Eyes rather small, feebly convex. 

 Mandibles apparently 4-toothed, flattened ; their outer borders sinuate towards 

 the base. Clypeus flat, ecarinate, trapezoidal, one and one-half times as long 

 as broad, with straight, somewhat crenate anterior border, about twice as long 

 as the posterior border, which is also straight ; the sides slightly curved out- 

 ward and diverging anteriorly. Frontal area distinct, triangular, as long as 

 broad. Frontal carinse far apart, more approximated and lyrate in front, par- 

 allel behind, forming the inner boundaries of rather deep scrobes for the bases 

 of the antennal scapes. Frontal groove distinct. Antennal scapes much 

 curved at the base, slender, but distinctly flattened, enlarged towards their 

 tips, which reach nearly to the posterior corners of the head. Thorax de- 

 cidedly narrower than the head, rather long, gradually narrowed posteriorly, 

 but with distinctly convex pleurae : in profile, the dorsum is rather flat, feebly 

 arcuate; epinotum with subequal base and declivity, both slightly concave 

 and meeting at a rounded angle. Petiole high, cuneate in profile, with thick 

 base and narrower summit, and both anterior and posterior surfaces flattened ; 

 border obtuse ; from behind, the scale is narrow at the base, expanding above, 

 with broadly rounded, entire upper margin. Gaster of the usual shape. Legs 

 slender. 



