BITHYS QUERCUS. 249 



the same marks are white, obliquely outwards, with dark space 

 between. The paler tint above the oblique line is very marked on the 

 6th abdominal segment, sometimes amounting to a great white dorsal 

 patch, whilst, on the 7th abdominal, the pale area is marginal. The 

 broad result, not looking to details, is a crust-brown larva, with a dark 

 central spot forwards, bordered with white (dorsal plain of thorax, 

 with flange white line), a length of serrated surface (the oblique lines 

 giving this effect), then a pale dorsal mark at the other end running 

 obliquely backwards to the margin, with the small portion beyond 

 paler. There are still two dorsal and lateral crests of hairs (about 

 0*25mm. long), too numerous to recognise as those of tubercles i, ii, 

 or any other primary hair. Head shining, black. On May 16th, this 

 larva moulted to last skin. It is to be noted that, in the third instar, 

 hairs, etc., are more numerous than in the second, e.g., on each side 

 of the prothoracic plate are about thirty hairs and eight or nine lenticles. 

 The plate itself is about 09mm. across, and is rather more diamond- 

 shaped ; about 100 hairs between the dorsal line and spiracles ; on the 

 abdominal segments six or seven dorsal ones of these are very large, 

 and one might select two of these as being the seta? of i and ii ; the 

 longest hairs are about 0'6mm., i.e., the same length as the longest 

 hairs in the second instar ; the lateral flange, and marginal 

 groups are still distinct, the lateral has a number of larger hairs, the 

 marginal separated from it by a narrow clear space ; there is again a 

 little group of 20-25 hairs (about 0*lmm. long) at the base of the prolegs. 

 There are two or three small lenticles below and behind each spiracle, 

 and appearing to be attached to it, and five or six larger ones above it; 

 there are two or three small ones in the dorsal mass of hairs, one or two 

 in the lateral and in the marginal groups. The small (0'24mm. 

 across) round anal plate has eight or nine hairs and a lenticle on 

 each side. The prolegs have about thirteen hooks to each pad, alter- 

 nately long and short, and about ten on the outer row, which are 

 the smaller, and vary a very little, but irregularly, in size. The anal 

 prolegs are much the same, but want the outer row of hooks. There 

 is no trace of gland arrangement on the 7th or 8th abdominal seg- 

 ments. The hair-bases have the complicated structure giving the 

 petaloid aspect, but the margins have not the segments crenately 

 rounded ; from the central circle, to which the hair is attached, there 

 run to the margin black lines, usually four or five in the bases to the 

 smaller, but eight or nine or more in the bases to the largest, hairs. A 

 good many hairs, chiefly on the " slope," and especially posteriorly, have 

 a curious structure, very curved (like a scimitar), or even angulated, 

 apparently rather flat, the middle of the hair very broad, and pro- 

 jecting- in very marked angles, by the development in excess of the 

 irregularities that are, elsewhere, mere spicular serrations. Third 

 instar (laid up for last moult, May 25th, 1906) : Length, 10mm. ; 

 width, 3mm.; height, 2-8mm. Hairs tolerably uniformly distributed, but 

 longer ones along the sides and along the dorsal ridges, about 0-6mm. 

 long, general hairs about - 04mm. ; all very pale brownish, those on 

 slopes arising from dark bases. Dorsal lozenges bounded by yellowish 

 dorsal (ridge) line and oblique line, pale browm within the oblique line, 

 margined with darker below. Viewed from the front, the dorsal ridges 

 appear close together (0-3mm. apart) ; the slope long (nearly 2-0mm.), 

 not flat, but full and rounded ; the dorsal ridges, or, rather, the yellow 



