396 FORTY-EIGHTH EEPOKT ON THE STATE MUSEUM 



long and slender: sette on the basal portions of the three distal segments with 

 a more or less verticillate arrangement; on the apical portions the arrange- 

 ment is more irregular. 



Wings hyaline and invested with numerous short hairs. The first longi- 

 tudinal vein (the first branch of radius) joins costa before the fork of the fourth 

 longitudinal (media). The venation is carefully represented in figure 1. The 

 halteres are long; basal half slender and partially segmented; distal portion 

 spatulate, — figure 4h. The scutum of the mesothorax is produced into a 

 marked dorsal hump, which bears one or more stout setae, — figures 1, la, 4, s'. 

 The scutellum of the mesothorax has a more or less granulated surface. The 

 hind coxa of the male extends to the basal third of the abdomen; in the femala 

 the hind coxa extends to about the basal fourth ; the hind femur is twice the 

 length of coxa; tibia one-fourth longer than femur; tarsi about equal to femur; 

 middle legs shorter and fore legs still shorter than the hind legs; one apical 

 spine occurs on the fore tibia and two on the middle and hind tibiae. 



The abdomen in both sexes is composed of nine segments; general form con- 

 ical. The apical portion in the female quite extensile; on the eighth segment, a 

 pair of ventral valves and between them a pair of slender processes; on the 

 ninth segment, a pair of lateral valves, the apical portion of which is nearly 

 circular, — figure 9. The abdomen of the male is shorter and apparently 

 stouter; due to shortness of the terminal segments; the terminal segment bears 

 within the larger jointed appendages a smaller pair of unsegmented, slightly 

 diverging appendages; the apical fourth of these inner appendages is thick- 

 ened, margin setose; beneath the dorsal plate a slender median organ may be 

 seen arising from a forked base, — figures 11, 11a. 



Length of body, 2.5 mm.; of wing, nearly 3 mm. Described from 30 females; 

 10 male?. 



Explanation of Plate I. 



Fig. 1. — Manure gnat, Sciara coprophila. 



Fig. la. — Scutellar hump of the same, more enlarged. 



Fig. 2. — .Head of the same: a, antenna; p, palpus. 



Fig. 3. — Portion of the compound eye still more enlarged and showing the 



relative proportion of chitine to the facets. 

 Fig. 4. — Lateral aspect of the thorax: c, c, c, insertion of thecoxee of thepro- 



meso- and m eta- thorax ; h, halter; S, spiracle; s, scutellar hump ; 



IV, base of wing. 

 Fig. 5. — 8th, 9th, and 10th segments of the antenna of the greenhouse gnat. 



Sciara caldaria. 

 Fig. 6.— Ditto of S. coprophila. 



Fig. 7. — Terminal segments of the palpus of S. caldaria. 

 Fig. 8. — Palpus of S. copropMla, showing the sensory pit on the second 



segment. 

 Fig. 9. — Lateral valve of the female of S. coprophila. 

 Fig. 10. — Ditto of S. caldaria. 



Fig. 11. — Dorsal aspect of the terminal segment of the male of S. copropMla: 

 d, dorsal plate; i, inner, o, outer appendages. 



