DURHAM DIPTERA. 3 1 



75 (70). Squamae absent or rudimentary. 



MUSCID.E ACALYPTERjE. 



76 (105). V.I. a. distinctly present, and nearly as thick as V.l.b., 



which latter generally ends in the fore margin at 

 or beyond the middle of the wing (V. 31, 32, 34). 



77 (84). Vibrissas or mouth bristles present, that is one or two 



bristles much longer and stronger than the hairs 

 that may be present (VII. 2). 



78 (79). V.4 4 four or five times as long as V.4 3 , that is X.5 2 



very much nearer to X.4. than to the wing margin, 



measuring along V.4. 



Heteroneurid^; (XXXVII.) 



79 (78). V.4 4 about equal to V.4 3 , or only a little longer. 



80 (81). Costa with a row of distinct spines, in addition to the 



ciliation (VII. 14). Helomyzid^ (XXXVI.) 



81 (80). Costa without a row of spines, only ciliated. 



82 (83). Fronto-orbital bristles present ; if absent, then body 



never shining black. Cordylurid^ (XXXIV.) 



83 (82). Fronto-orbital bristles absent, body always shining 



black. Sepsid2E, part (XLVI.) 



84 (77). Vibrissas absent, mouth at most with short hairs, but 



often bare, or if the hairs are strong then they are 

 all about the same length and strength (VII. 1, 3,4.) 



85 (88). Antennae very long and horizontal, second joint as 



long, or longer than the third, the upper edge of 

 which is concave (III. 54 & VII. 1). 



86 (87). Profile not triangular, the face being perpendicular, 



or only slightly retreating. 



Sciomyzice, part (XXXVIII.) 



87 (86). Profile triangular, the face retreating almost horizon- 



tally (VII. 1). Ortalid^e, part (XLI.) 



88 (85). Antennae not long, or, if long, drooping, not horizontal, 



second joint always shorter than the third, the 

 upper edge of which is straight or convex. 



89 (90). Brown or black shore flies, with flat horny thorax, 



and with strong mouth hairs. 



Phycodromice (XXXV.) 



