WERNER MARCHAND 83 



after the larva had withdrawn, that a small portion of the tail end of 

 the animal was left untouched — no doubt in consequence of his 

 being unable to penetrate to the small end of the whorl in the shell — 

 and also the skin of the remaining part and the horny tongue 

 membrane. 



Walsh's description of the larva of Tahanus atratus, including that 

 of the imago which serves to establish its identity as to species, is 

 given here: 



" Tabanus — ? Imago male. Blackish. Legs blackish, wings brownish fuscous. 

 Length 0.70 inch. Expanse L30 inch. One decayed specimen came out between 

 June 14 and July 14, 1861, from a larva found early in June." 



"Larva, from the living specimens, obtained August 14, 1860, and September 

 2, 1863. Length 2.25 inches when extended, 1.75 inches when contracted; di- 

 ameter 0.25 to 0.30 inch. The specimens found in 1863, 0.25 inch shorter. 

 Body cylindrical, twelve-jointed, the three or four terminal joints much tapered 

 at each side of the body, but more so anteriorly than posteriori}^, and joints one 

 and eleven, each with a retractile membranous prolongation at tip. Joints one 

 to ten are subequal; eleven is about two- thirds as long as ten, and twelve about 

 one-fourth as long, and 0.5 inch in diameter. Color a transparent greenish white, 

 paler beneath, on the anterior and posterior margins of joints two to eleven, the 

 anterior annulus laterally connected with the posterior by two to four dark green 

 lines. On the dorsum of four to nine, and more obscurely on ten, a dark green 

 basal triangle, extending half way to the tip; joint one with paler markings, and 

 with no dark annulus behind; joint twelve entirely fuscous. Plead small, appar- 

 ently fleshy, pale, truncate-conical, 0.03 inch wide, and about 0.04 inch long in 

 repose, inserted in joint one without any shoulder. The trophi occupy two- 

 thirds of its length, but it has a long cylindrical internal prolongation, extending; 

 to the middle of joint two, which is som.etimes partially exscrted, so that the headi 

 becomes twice as long as before. All the trophi are pale and apparently fleshy 

 except the mandibles, which are dark colored and evidently horny, and they^ 

 have no perceptible motion in the living insect. The labium is slender, a little 

 tapered, and three times as long as wide, on each side of and beneath which is a 

 slender thorn-like decurved brown-black mandible. The labium resembles. 

 the labrum, but is shorter, and on each side of it is a slender palpiform but exar- 

 ticulate maxilla, extending beyond the rest of the mouth in an oblique direction. 

 No palpi. On the vertex are a pair of short fleshy exarticulate filiform an- 

 tennjE, and there are no distinct eyes or ocelli. In the cast larva! integument 

 the entire head, 0.25 inch long, is exserted, and is dark colored and evidently 

 horny, all the parts retaining their shape except the antennze, labrum, and 

 labium. The whole head has here the appearance of the basal part of the 

 leaf of a grass plant, clasping the origin of the maxillae on its posterior half, and 



