24 STRUCTUEE OF CERTAIN DIPTEROUS LARV^. 



Muscid B. 

 (Plate III, figs. 40-43.) 



This larva is plainly larger than that of the house fly, and less 

 tapering in front; the head is blunt and rounded, and the papillae 

 are not distinct ; there is but one mandible ; the anterior spiracles are 

 six-lobed. The fifth segment has below on base a slightly swollen 

 area which is transversely striate; the sixth and following segments 

 have on the ventral base the usual fusiform area, but little swollen, 

 faintly divided on the median line, and with many longitudinal teeth 

 or short ridges; the dorsum is smooth. The anal area is sunken, but 

 the upper margin shows a median lobe with three smaller lobes each 

 side; surface of last segment smooth; stigmal plates small, deep 

 black, about their diameter apart and each with three sinuous slits, 

 similar to those of Musca. 



Several specimens sent from New York that were passed by an 

 epileptic patient in December and January. This species is closely re- 

 lated to the house fly, but to what genus it belongs is yet uncertain — 

 perhaps to Graphomyia. 



Lyperosia irritans L. 

 (Plate I, figs. 5-7.) 



The body of the horn fly larva is very slender, especially in front. 

 Head bilobed, each lobe with a tim^ papilla; one mandible, not very 

 large. The anterior spiracles have six lobes. The general surface 

 of the body is smooth or very minutely striate; the fourth ventral 

 segment at base shows an area with tubercles or small teeth ; begin- 

 ning with the sixth, each segment has on the ventral base the trans- 

 verse, fusiform, swollen area, with two rows of longitudinal teeth or 

 tubercles, and also each ventral segment shows a transverse groove 

 before the middle, and the penultimate segment has at base beneath 

 a spinulose fusiform area. The last segment is rather evenly rounded 

 above, the stigmal plates close together, and each with three winding 

 slits, as in allied forms. The anal area is moderately protuberant, 

 mostly black, and shows below a smooth submedian lobe each side, 

 and laterad of this a larger smooth lobe ; above is a pair of more promi- 

 nent, smooth, black tubercles; each side of these is a smaller cone and 

 above is a transverse row of teeth. 



Specimens came from cow manure containing also the larvae of 

 Pseudopi/rellia cornicina. 



Stomoxys calcitrans L. 



(Plate I, figs. 8-10.) 



The larva has been described and figured by Newstead and later by 

 Hewitt. It is similar in shape to that of the house fl}^, with a single 

 great hook or mandible; the anterior spiracles have five lobes; the 



