IGO LDccernber, 



METAMOEPHOSES OP XYLOPHAOUS CINCTUS, F., AND 

 X. ATER, F. 



BY F. BUCHANAN WHITE, M.D., F.L.S. 



When in Braemar a year or two ago I occasionally came across 

 some very curious dipterous larvae, living under the bark of dead 

 pines and birches. These larvae, though found on such very different 

 plants, were so similar in appearance, that I concluded that they 

 belonged to one species ; and it was only on rearing them to the 

 pei'fect state that I found that the one under pine bark belonged to 

 JS^ylopJiagus ductus, F., and the other to X. ater. 



The following is a description of the larva and pupa of X. cinctus, 

 from notes made at the time : — 



Larva cylindrical, slightly tapered to each extremity ; shining dirty whitish ; 

 integuments tough ; segments twelve. The head is a shining black, horny, triangular 

 beak, slightly flattened, and with the apex prolonged. Near the middle of the pro- 

 longation is a narrow longitudinal furrow (or opening ?) on each side. On each side 

 of the centre of the apex is a slit or furrow, and near the apex below is an oval 

 opening (the mouth). The head is furnished with a few erect brown hairs. The 

 2nd segment is much wider than the head, and nearly covered above with a square 

 chocolate-coloured scaly plate, lacerated in several places, more especially by two 

 longitudinal lines which divide it into three equal parts. Near the posterior angles 

 of the plate are the oval spiracles. There is a trace of the plate on the under-side of 

 the segment, on the outer and anterior edges, widest at the anterior angles, and 

 nearly obsolete in the centre of the anterior margin. Between the 2nd and 3rd 

 segments is a series of small, square, brownish scales, rounded at the ends. This series 

 is continued all round the division between the segments, but is more or less in- 

 terrupted at the sides, and the scales are half on one segment and half on the otlicr. 

 There are similar series between all the other segments, but the scales are smaller 

 and placed in a double row, one on each side of the fold. 3rd and 4th segments, 

 with shining chocolate-coloured plates, as on the 2nd, but narrower (on the 4th 

 narrower than on the 3rd), and lacerated in a similar manner. No plates on the 

 under-side, and no spiracles. 5th to 11th segments similar to each other. At the 

 centre of the anterior margin (except of the 11th segment above) is a rather broad 

 space (occupying about one half the breadth) , covered with rows of erect brownish 

 corneous points, small in the three or four uppermost rows, but larger, and connected 

 — the points of one row with those of the other — by corneous ridges in the two lower 

 rows. About a fourth of the length from the hind margin is a row — going round the 

 segment (except on the under-side of the 5tli) — of flattened spiny hairs, of various 

 lengths, adpressed and directed backward ; and (except on the 5th segment) halfway 

 between this row and the front margin, is a short oblique row of small brown scales 

 (similar t9 those between the segments), lying halfway between the mesial line and 

 the sides. The under sui'face of the segments is like the upper, but the oblique line 

 is longer. On the side of each segment is a spiracle (small, round, and apparently 

 "blind "), with a short, stout, triangular spine below it. The 12th segment is quad- 



