CYLINDROTOMA. 301 



grayish tinge, and the stigma is likewise more distinctly colored. 

 The paleness of my two American specimens may be accidental ; 

 still, they would show at least a vestige of the spot on the rneta- 

 thorax, if it occurred in better-colored specimens. 



2. C. nodicornis 0. S. % and 9.— Obscure flava, capite nigro, 

 thorace nigro-vittato, antennis moniliformibus, articulis earuin brevi- 

 bus, subcordiformibus ; cellulis posterioribus quatuor. 



Dark yellow, head black, thorax with black stripes, antennae nioniliform, 

 their joints short, almost heart-shaped ; four posterior cells. Long. corp. 

 0.4—0.42. 



Syn. Triogma nodicornis 0. Sacken, Proc. Entom. Soc. Phil. 1865, p. 239. 



Head black, shining ; palpi brownish ; antennas dark brown, 

 reaching a little beyond the basis of the abdomen in the male and 

 somewhat shorter in the female ; two basal joints and the basis 

 of the third brownish-yellow ; first joint cylindrical, of moderate 

 length; the second .short; the joints of the flagellum, especially 

 the middle ones, are not much longer than broad, expanded on 

 the under side so as to appear almost heart-shaped, and con- 

 nected by short pedicels, so as to make the antenna appear 

 moniliform ; the last joint is abruptly narrower than the pre- 

 ceding and about twice its length, subcylindrical ; it shows a 

 coarctation in the middle, which is more apparent in some (fresh) 

 specimens than in others, and then the antennas may be taken for 

 17-jointed; in the female the. joints of the flagellum are much 

 less expanded, and only seven or eight intermediate joints have a 

 strikingly heart-shaped appearance ; towards the tip, they become 

 gradually narrower ; in both sexes, the antennas are clothed with 

 a soft, dense, pubescence, much denser on the under side, and 

 much more striking in the male than in the female ; besides, each 

 joint has several verticils about the middle. Thorax honey- 

 yellow, with three black, shining, often confluent stripes ; sternum 

 between the first and second pairs of coxas, black, shining ; this 

 black coloring is extended upwards, across the pleuras, in the 

 shape of a black, but not shining stripe ; a black opaque spot 

 near the base of the halteres, aciculate on its surface ; metathorax, 

 or at least its posterior part, black, its surface rugose (very dark 

 specimens, with confluent thoracic stripes, have all these spots 

 and stripes darker and more extended ; those specimens, on the 

 contrary, which have the thoracic stripe separated by yellow, 



