AMORPHA POPULI. 485 



under the rounded extension formed by the anal angle of forewing. 

 In some specimens the wing presents nothing but uniform finely 

 granulated or rough surface. In a well-marked one, however, 

 the rough points arrange themselves in transverse lines, interrupted 

 by fine, impressed, longitudinal lines representing the nervures, 

 against which they are rather stronger; in other cases these higher 

 points coalesce and represent the nervures by a ridge, without 

 the impressed line. Poulton's line is very vaguely expressed by 

 the surface being sloped off to the margin by a rounded chamfer 

 and by a little change of surface texture. At the centre of the 

 wing base is often a small, smooth, almost glazed surface, with 

 a distinct rounded nodule, usually polished and different from the 

 roughnesses of the general sculpturing. The dorsal sculpturing 

 of the mesothorax may be minute and fairly uniform ; there is, 

 however, usually a vague suture marking off the wing-base, and 

 a longitudinal central one extending to the head and into the 

 first abdominal segment ; this may be a single or double ridge. 

 The general character of the sculpturing over these segments is 

 a set of rather sharp points tending to get into continuous ridges, 

 something like those on antennae. The abdominal segments present the 

 usual subsegmentation with varying distinctness. The intersegmental 

 subsegment is very distinct laterally on 3, 4, 5, 6 and 7 ; in front of 

 this, four other subsegments may be made out, usually very obviously 

 on the 3rd abdominal, but more frequently on the other segments 

 two only can be distinguished with any certainty ; that they are, how- 

 ever, there substantially, is evidenced by slight indications in the 

 arrangement of the rough ridges, even in the specimens in which 

 they are most obscure ; a faint indication of a narrow subsegment 

 in front of these often exists on abdominal segments 3 and 4. 

 The sculpturing of these abdominal segments is very labyrinthine, 

 in some lights one takes it to be longitudinal, in others transverse. 

 The fine, rather sharp ridges run into one another in a wave-like 

 manner, with more or less fusiform hollows between ; dorsally, a 

 longitudinal arrangement is dominant, with much stronger ridges 

 at the anterior borders of the segments, ventrally, a somewhat more 

 transverse direction prevails ; the anterior border of abdominal 

 segments 5 and 6 has a rather sharp edge, only seen when the 

 incisions are well opened, when, also, further smaller and smaller 

 transverse ridges are seen to succeed each other right up to 

 the intersegmental membrane ; below this, on abdominal segments 

 5, 6, and 7, is another transverse ridge, followed by two or three 

 others in the spiracular region; these are really parts of the general 

 arrangement of sculptured ridges, but are here very prominent, and 

 separated from the others by their special direction, and the diminu- 

 tion comparatively of the subsidiary interlacing ridges ; they produce, 

 on these three segments, a definite projection overhanging the 

 spiracle ; on the 5th and 6th, the margin marking off the inter- 

 segmental subsegment is a definite raised line ; the scar of the 

 caudal horn may be quite obsolete, but is usually a depression, with 

 sometimes a prominence at its anterior margin. The scars of the 

 ventral prolegs are not absent in any specimen examined, but are so 

 various that apparently they might be ; in some they are merely 

 a small smooth spot from which the ridges of sculpturing radiate, 



