356 Annals of the Carnegie Museum. 



Synopsis of South American Species of Tridactylus. 



A. Pronotum throughout quite closely- and rather strongly punctate. Entire 

 surface of the bodj' and legs opaque or lusterless. General color deep 



hlack. Size medium (length of body, 7-S mm.) obscurus sp. nov. 



A A. Pronotum and other portions of the body and legs glabrous, almost impunc- 

 tate. General color variable. Size also variable (5-8 mm.) 

 b. Size larger and form moderately robust (7-8 mm.). Color pallid, but more 

 or less variegated, the darker markings irregular and vague in their 



outline. [Bolivia, Paraguay, and Argentina] australis sp. nov. 



bb. Size smaller (4.75-5 mm.). Color darker, or at least with the darker mark- 

 ings definite and well-defined. 

 c. Form moderately robust. General color black, reminding of the much 



larger obscurus. [Brazil & Bolivia] atratus sp. nov. 



cc. Form rather slender. General color pallid, but with well-marked fuscous 

 patches on the pronotum, tegmina, and legs. [Bahia, Brazil]. 



politus sp. nov. 



9. Tridactylus obscurus sp. nov. 



Rather above the medium in size, a very dark-colored, almost black, 

 insect, the chief characteristic of which is its dull or opaque surface 

 and the closely punctulate pronotum and front. 



Head moderately large, the front between the antennae broad and 

 convex, closely and deeply punctate, the ocelli large and prominent, 

 clypeus large, and with the apex broadly and evenly rounded. Pro- 

 notum without a well-defined transverse impressed line anteriorly. 

 Tegmina broad, a little more than one-half the length of the abdomen, 

 their apex broadly rounded. Wings lengthily caudate, reaching well 

 beyond the apex of the hind femora and the tip of the abdominal 

 ai)pendages. Hind tibiae provided with large natatorial appendages, 

 the lateral canthi furnished with several large teeth or serrations and 

 the superior claws strongly hooked at their apex. Last ventral seg- 

 ment broadly rounded at its apex, the preceding one a little broader 

 than long, its apex bilobed ( 9 ) or entire (cf ). Anterior tibia? broadly 

 longitudinally canaliculate internally, the apex four-spined and some- 

 what fissatc at its middle. 



General color, as stated above, dull black, in some specimens showing 

 a tendency towards variegation with pale markings on the tegmina 

 and femora. Wings pallid, with the dorsal edge beaded with fuscous. 

 Underside slightly paler, but still infuscated or tinged with fuscous. 



Length of body 9 & cf , 7-^ nim. to tip of wings, 9.5-10.5 mm. 



Habitat. — The type ( 9 ) ccMiies from Santarem, Brazil, where it was 



