NOTES TOWARDS A LIFE-HISTORY OF POLYOMMATUS DONZELTI. 13 



upper one slightly more so than the lower. The former is practically 

 parallel with the dorsal line, but the latter has a slight ventral slope 

 from the anterior margin backwards, so that, on each segment, the 

 commencement of the stripe is slightly more dorsal than the conclusion 

 of that of the preceding segment. The flange is also reddish, with the 

 exception of the outermost portion, and, in later stages of this instar, 

 the colour extends ventrally as far as the marginal flange, and dorsally 

 to a level with the spiracles. The prothorax and the final abdominal 

 segments, owing to the converging of the various bands of colour, 

 appear much more suffused with red, and only show here and there 

 traces of ground colour. This stage is noticeable for the great increase 

 in the number of secondary tubercles, the whole area of the body being 

 more or less thickly covered with them. The tubercles of the previous 

 instar can still be traced by their larger size. These, as well as many 

 of the smaller ones, possess two or three spicules, arranged in a ring 

 about midway between the base and apex. The lenticles also have a 

 circle of usually five similar spicules around the black ring, giving 

 them a star-shaped appearance. On each dorsal ridge is a group of 

 three tubercles, arranged in the form of an arc, with the convex side 

 outward. As the central tubercles approach each other closely, the 

 whole six tubercles present the appearance of a semicircle across the 

 dorsal area of the body. Within this is enclosed a group of three or 

 four smaller tubercles, while, on the anterior margin, are usually two 

 minute tubercles. This arrangement is slightly modified on the 2nd 

 and 3rd thoracic segments by the addition of a large tubercle anterior 

 to the three already mentioned, especially noticeable on the mesothorax, 

 and further by the number of tubercles contained within the semicircle 

 being increased to six, these forming, in their turn, a horseshoe curve. 

 the open end of which points forward. Of the lateral lenticles, so 

 prominent in the first instar, the smaller has disappeared entirely, but 

 the other, much reduced in size, remains, except on the mesothorax, 

 where it is entirely absent. Between this lenticle and a large tubercle 

 occupying a position similar to tubercle iii of the previous instar, are 

 scattered five or six minute tubercles with correspondingly small seta?. 

 One of the most characteristic features of this instar is a group of three 

 lenticles, occurring between tubercle iii and the spiracle, and at first 

 easily to be confused with this. One is anterior and ventral to the 

 tubercle, the other two posterior, and placed vertically above each 

 other. On the final abdominal segments the position of these seems 

 to vary greatly, and is not even constant for the same segment on 

 different larvae ; the number, also, is often reduced. On the 3rd 

 thoracic segment the position is reversed, two being anterior and one 

 posterior, the more dorsal of the anterior lenticles being slightly above 

 the- tubercle. On the mesothorax only two very minute lenticL 

 be found. Several small tubercles also occupy the supraspiracular area. 

 On the flange is situated a group of six or seven tubercles, of which 

 three, occupying practically similar positions to those of the first instar, 

 are considerably larger. This number is increased on the fcho 

 segments. The space between the flanges, as well as the marginal 

 ■ itself, is also occupied by several small tubercles, with occasional 

 lenticles. On the prothorax the anterior margin is bordered by a 

 double row of tubercles. The remaining space is occupied by tubercL s, 

 which may be divided into three groups, converging from points on 



