wheeler: ants of the genus opisthopsis, 345 



of the head, the larger individuals having the region in front of the 

 eyes more convex on the sides than the smaller individuals. In one 

 speclos (0. jocosus) the dimorphism is very distinct. 



In the figures accompanying this article I have endeavored to indi- 

 cate the extent of the black or dark brown markings by stippling. Tiie 

 color of the eyes is peculiar. Tlie retinal pigments are either very 

 unstable and fugitive, so that they disappear in alcohol, or the eyes 

 are in many of the species of an unusual pale gray or whitish color in 

 life. Unfortunately I failed to note the eye-color in living individuals. 

 In the descriptions I have recorded it as it appears in the dried speci- 

 mens. 



Opisthopsis Emery. 



Worker. Small, monomorphic or slightly dimorphic; thorax, pet- 

 iole, and gaster resembling the corresponding parts in Camponotus. 

 Anterior femora incrassated. Head elongate, subtrapezoidal, with 

 long, straight or more or less convex or inflated cheeks. Eyes very 

 large, prominent, elliptical and finely facetted, at the posterior corners 

 of the head. Ocelli usually absent, the anterior ocellus sometimes 

 present. Mandibles small, triangular, 5-toothed. Maxillary palpi 

 6-jointed, labial palpi 4-jointed. Clypeus well-developed, more or 

 less carinate or subcarinate, its anterior border entire, projecting over 

 the base of the mandibles as a broad, rather rounded lobe. Antennae 

 12-jointed, inserted at the sides of the frontal carinae some distance 

 behind the posterior clypeal suture, so that the antennal and clypeal 

 fossae are distinctly separated. Antennal funiculi nonclavate, all 

 the joints distinctly longer than broad. Frontal area large, indistinct, 

 subtriangular or trapezoidal; frontal carinae moderately long, rather 

 far apart, diverging posteriorly. Epinotum unarmed, more or less 

 angular. Petiolar scale thin and anteroposteriorly compressed. 

 Proventriculus long and slender, the calyx straight, with non- 

 reflected sepals. Body smooth, more or less shining, finely shagreened. 

 Pilosity and pubescence feebly developed. 



Female. Larger than the worker, with broader head and usually 

 6-toothed mandibles. Eyes and ocelli well-developed, the former 

 much as in the worker. Thorax, petiole, and gaster as in Camponotus, 

 the thorax elongate elliptical, the petiole anteroposteriorly compressed. 

 Wings also similar but with small but distinct, triangular discal cell. 



Male. Not larger than the worker, very similar to the male of 

 Camponotus. Maxillary palpi 6-jointed, labial palpi 4-jointed. 

 Mandibles well-developed, pointed, usually edentate. Eyes and 



