126 INSECUTOR INSCITlit MENSTRUUS 



deeply infuscate than wings. Erect weakly spinelike macrochaetae on 

 disk of scutellum. Abdomen rather thickly bristly on sides anteriorly, 

 and anal segment well bristled. Only one preacrostichad and one post- 

 acrostichal bristles. Male front at vertex a little less than eye-width. 



The above three genera, Signosoma, Signosomopsis, and Eusigno- 

 soma, are small South American forms representing in the Andean region 

 the signifera colorational-type, which is that with the sign-mark on anaJ 

 segment. They sure characterized by a peculiar conformation of the ter- 

 gum of abdomen whereby the intermediate segments are pushed forward 

 in middle and the anal segment is much extended forward on median 

 portion, its front border being thus highly arcuate. This has apparently 

 resulted from the necessity of enlarging the dorsal surface of anal segment 

 so as to increase the size of the sign-mark, whose development appears 

 to be practiccJly confined thereto. 



Uruhuasia, new genus. 



Differs from Eusignosoma as follows : Described from male only. 

 Abdomen not so rounded, more elongate and narrowed, being but little 

 wider than the thorax, narrowed apically and not emarginate. Length 

 of anal segment not over one and one-fourth times that of third segment. 

 No conspicuous meurking on anal segment, but a faint pollinose pattem on 

 both third and anal segments after the plan of the pollen of anal segment 

 in Eusignosoma nigrum, with second segment eJso fmntly pollinose in 

 oblique view. Macrochaetae of anal segment covering the posterior half 

 of its dorsal surface and practically all of its ventral surface. Scutellum 

 with only ordincu-y macrochaetae, absolutely lacking spinelike macrochae- 

 tae ; two long lateral marginal pairs, one very weak apiceJ decussate pair, 

 disk wath several pairs of weak bristles irregularly disposed. Three 

 sternopleural bristles, three postsutural, one postacrostichaJ, and one pre- 

 acrostichal. Second abdominal segment with two median discal pairs of 

 macrochaetae, one pair in front of the other; two or three latercd discal 

 on each side, and a marginal row. Abdominal macrochaetae not spine- 

 like, ventral plates with only bristly hairs. 



Palpal bristlets present. Third antennal joint one and one-half times 

 as long as the moderately elongate second joint. Second aristal joint 

 moderately elongate, the arista subgeniculate. Male front at vertex rather 

 more than eye-width. Male cheeks fully two-thirds eye-height. Claws 

 distinctly longer than last tarsal joint. 



