316 DIPTERA OF NORTH AMERICA. [PART IV. 



pale at the basis, their latter half blackish ; tibiae black, with a 

 brown ring near the basis ; first joint of the tarsi black, white at 

 the basis ; the second and the third white ; the two last joints 

 black ; abdomen brownish-black, the posterior margins of the 

 segments, beginning with the second, paler. Wings hyaline. 



JSab. North America, not rare. Newfoundland, common 

 (Westw.) ; Nova Scotia (Brit. Mus.) ; Washington, D. C, not 

 rare ; Upper Wisconsin River (Kennicott) ; Florida, where I 

 caught it in March. This insect occurs early in the spring and 

 also, but more seldom, in autumn ; usually in the vicinity of 

 water, especially in woody localities. A number of Bittaco- 

 morphse, flying slowly, as they do, and keeping their feet, varie- 

 gated with snow-white, extended like the radii of a circle, present 

 a very striking appearance. 



Gen. XL VI. PROTOPLASA. 1 



Two submarginal cells, the second much longer than the first ; a sub- 

 costal cross-vein at the tip of the auxiliary vein ; a discal cell ; six pos- 

 terior cells, in consequence of the Jirst being divided in two by a supernumerary 

 longitudinal vein ; the penultimate posterior cell contains a supernumerary 

 cross-vein ; only a single longitudinal vein after the fifth vein ; anal angle 

 projecting, square. Antennae 15-jointed. Tibiae with spurs at the tip. 



Head elongated ; eyes separated by a moderately broad front 

 above, almost contiguous on the under side of the head ; epistoma 

 longer than broad ; the proboscis, together with its large, fleshy 

 flabs, is not much shorter than the head ; palpi longer than the 

 head, joints elongated. 2 Antennae (9 ?) apparently 15-jointed, 



1 I possess two, somewhat injured specimens of P. fitchii. Only a single 

 antenna seems to be entire, and I count 15 joints upon it. One of the 

 specimens has no head ; the neck of the other is so twisted that I did not 

 perceive its length, until my attention was called upon it by the descrip- 

 tion of Tanyderus Philippi ; this is the reason why the length of the neck 

 is not mentioned in Proc. Acad. Nat. Sci. Philad. 1859. 



2 In Macrochile Loew (comp. below) the length of the palpi is dependent 

 on the elongation of all the joints, not of the last chiefly, as in Ptychoptera. 

 The second and the last joints are represented by Mr. Loew as being of 

 equal length, and somewhat longer than the first and the third. In Tany- 

 derus Philippi, likewise, all the joints are elongated, the last not being 

 much longer than the preceding ones. As far as I can perceive, the palpi 

 of Protoplasa have a similar structure, although I cannot describe them 

 accurately from a dry specimen. 



