RHIPIDIA. 81 



Head tawny, somewhat grayish on the front ; antennae blackish, 

 under side of the first joint tawny ; proboscis and palpi brown, 

 the former paler at the basis. Thorax brownish, with three more 

 or less dark brown stripes ; pleurae paler ; metathorax brownish, 

 with a hoary bloom ; 'halteres infuscated, pale at the basis ; feet 

 tawny, tips of the femora, of the tibiae, and of the tarsi brown. 

 Abdomen brown, posterior margins of the segments paler ; venter 

 pale. Wings very slightly tinged ; stigma brownish ; the tip of 

 the first longitudinal vein is incurved towards the second, the 

 marginal cross-vein being apparently between it and the costa ; 

 the tip of the auxiliary vein is nearly opposite the middle of the 

 praefurca. 



Hab. Washington, D. C. ; Upper Wisconsin River (Kenni- 

 cott) ; Illinois (LeBaron). 



The proboscis of this species is very long, at least once and a 

 half the length of the thorax. I have seen the original specimen 

 of Limnobiorhynchus canadensis Westwood, in the author's own 

 collection; (compare the genus Toxorrhina.) 



Gen. III. RHIPIDIA. 



One submarginal cell ; four posterior cells ; a discal cell. Antennae 

 14-jointed; hipectinate, pectinate or subpectinate ; joints of the flagellum 

 always distinctly pedicelled. Rostrum and proboscis short. Feet slender ; 

 tibise without spurs at the tip ; empodia indistinct or none. The forceps 

 of the male is like that of Dicranomyia and consists of two immovable, 

 fleshy lobes, and a horny style on the under side (Tab. Ill, fig. 5 and 5a). 



Bhipidia is principally distinguished from Dicranomyia by the 

 structure of the antennae. This structure is most prominent and 

 peculiar in the male of JR. macalata M. ; the joints of the flagellum 

 (except the basal and the terminal ones) emit in this species two, 

 rather long, branches. In the two other North American species 

 and in the second European species (i?. uniseriata Schin.) the 

 joints of the flagellum bear only a single branch, which is shorter 

 than those of R. maculata. The females of all the species have a 

 moniliform flagellum, that is, the single joints are separated by 

 distinct pedicels ; the joints of the basal half of the flagellum are 

 somewhat projecting on the under side. 



The auxiliary vein reaches more or less beyond the origin of 

 the second longitudinal vein, and in this respect Bhipidia agrees 

 with those Xorth American Dicranomyise, which have spotted 



6 July 1868. 



