FUNGUS GNATS OF NOETH AMERICA. 75 



the postero-ventral angles of the hypopygial sclerite are pro- 

 duced ahnost as far as the tips of the articulated processes in 

 the form of slender, blunt almost spine-like lobes, in B. analis. 



27. Genus Dynatosoma Winnertz. 

 Verh. Zool.-bot. Ges. Wien. XIII, 947, 1863. 

 Front broad, anterior -margin not produced into a triangle, 

 vertex high; ocelli usually 2 in number, large; the middle one, 

 when present, very minute ; Thorax pubescent, margins setose, 

 scutellum semicircular v^ith setose margin. Legs stout,, hini 

 femora each usually with 3 ranges of stout setae on extensor 

 surface. Costa not extended beyond tip of Rs; subcosta nearly 

 half as long as the basal cell R and ends in Ri; branches of the 

 cubitus widely divergent; first anal long but incomplete, strong. 



Table of Species. 



a. Cubitus forks distad of the basal section of the radial sector; wing 

 with distinct spots; 3 ranges of setae pn each hind tibia, 

 b. Thorax largely and abdomen, fuscous; hypopygium (Fig. 58). 



I. ' n'igrinn n. sp. 

 bb. Thorax largely and basal portion at least of abdomen, yellow, 

 hypopygium (Fig. 59). 2. fulvida. 



aa. Cubitus forks proximad of the base of radial sector; wing un- 

 spotted ; 2 ranges of setae on each hind tibia, 

 b. Thorax black. 3. ' thoracica. 



bb. Thorax fulvous. 4. placida n. sp. 



I. Dynatosoina nigrina n. sp. 

 IMale. Length 5 mm. Head fuscous, antennas subfuscou-; 

 basal 3 or 4 joints and. palpi yellowish. Thorax fuscous, the 

 narrow posterior angles of the mesonotum and the humeri, 

 widely, reddish yellow; hairs and setae yellow. Abdomen 

 blackish, the hind margins of the segments narrowly and indis- 

 tinctly, yellow; hairs, appressed, yellow; hypopygium (PI. 7, fig. 

 19, Genera Insectorum, Fasc. 93) and (Fig. 58). Coxse yellow, 

 middle and hind ones each with an oval black spot near the apex 

 on the outer side; femora and tibiae, yellow, the bases of all and 

 the apices of middle and hind femora, black, tip of hind tibia 

 black ; tarsi brownish. Wing grayish hyaline, marked with a 

 large brown central spot, a preapical fascia and a faint grayish 

 apical margin (Fig. 183). Halteres yellow. Mass>. 



