/' 



ne, 1909.] Wheeler : North American Formicid.e. 83 



6. Lasius (Acanthomyops) occidentalis, new species. 



Wot-ker. — Length 2.5-3 ™ni- 



Head rectangular, a little longer than broad, with straight posterior border and 

 very feebly convex, subparallel sides. Mandibles with 7 or 8 unequal teeth. Eyes 

 small. Clypeus feebly carinate. Antennal scapes not extending beyond the posterior 

 corners of the head. Funiculus gradually enlarging towards the tip, joints 2 and 

 8-10 as long as broad, joints 3-7 somewhat broader than long. Thorax of the 

 usual shape in the subgenus. Petiole as high as the epinotum, about half as broad as 

 high, compressed anteroposteriorly, with slightly convex anterior and flat posterior 

 surface ; seen from behind rectangular, with the sharp transverse upper border emargi- 

 nate in the middle. Legs rather long, feebly compressed. 



Surface of body shining, finely and rather sparsely punctate, head and clypeus 

 more glabrous. Mandibles striatopunctate. 



Pilosity and pubescence golden yellow ; the former long, erect, obtuse, moder- 

 ately abundant, confined to the body ; the latter more abundant, covering the body 

 and appendages, but little longer and denser on the gaster than elsewhere. 



Yellow ; head slightly reddish ; borders of clypeus and mandibles dark red ; 

 teeth of latter black. 



Female. — Length 4.5--5'5 nun. 



Head more rectangular than in the worker, distinctly longer than broad, with 

 very straight, parallel sides and feebly excised posterior border. Eyes flattened, just 

 behind the middle of the head. Antennal scapes reaching half way between the eyes 

 and the posterior corners of the head, incrassated at their distal ends ; all the joints 

 of the funiculus, except the first and last, somewhat broader than long. Thorax a 

 little more than twice as long as broad, elliptical from above, through the wing inser- 

 tions but little broader than the head ; mesonotum and scutellum flat ; epinotum with 

 a short base rounding into the rather steep declivity. Petiole like that of the worker. 

 Gaster longer than the thorax, narrow, with subparallel sides. Legs rather long, 

 somewhat compressed laterally, but not dilated. Tarsi slender, hind metatarsus much 

 shorter than the hind tibia. Wings long (5.5 mm.), discal cell rarely incomplete or 

 absent. 



Pilosity, pubescence and sculpture like those of the worker, but the pubescence is 

 longer and on the gaster much denser and more conspicuous, so that the segments 

 appear subopaque. 



Color resembling that of the worker, but somewhat more brownish throughout. 

 Wings yellowish hyaline, slightly infuscated towards their bases, with brown veins 

 and stigma. 



Male. — Length 2.6-3 rnm- 



Head, excluding the mandibles, somewhat broader than long, slightly broader 

 behind than in front, with straight posterior border. Eyes hairless, convex, in the 

 middle of the sides of the head. Mandibles edentate. Clypeus broadly rounded in 

 front, convex and subcarinate in the middle. Frontal furrow distinct. Antennae 

 slender ; scapes reaching somewhat beyond the posterior corners of the head ; funiculi 

 with cylindrical, subequal joints ; first joint feebly swollen, longer than the second. 

 Thorax rather robust, through the wing insertions broader than the head. Declivity 

 of epinotum more sloping than in the female. Petiole like that of the worker but 

 more compressed anteroposteriorly. Gaster elliptical, somewhat flattened dorsoven- 

 trally. Discal cell of wings often lacking. 



