388 BRITISH BUTTERFLIES. 



Imago. — 25mm. -32mm. $ ; all the wings azure-blue, with a delicate 

 blackish margin, rather more denned in apical area ; fringes white, 

 delicately latticed with blackish at end of nervures. 2 • Somewhat 

 paler blue, with ill-defined discoidal spot and broad blackish-fuscous 

 margin to forewings ; a fine black marginal edge to hindwings, 

 followed by a series of interneiiral black marginal spots ; fringes 

 white, more distinctly latticed with blackish. Underside bluish- 

 white, with indistinct linear discoidal spot, a transverse submarginal 

 row of fine black linear marks across both wings, 3 to -5 scattered 

 dots near base of hindwing, and an obsolete series of marginal 

 lunules to both wings. 



Sexual dimorphism. — The sexual dimorphism of Celastrina argiolus 

 is superficially most marked, the male being almost entirely blue 

 whilst the female exhibits a small black discoidal spot, as well 

 as a broad black outer marginal band, varying in width and 

 intensity, on the forewings, and a row of marginal spots on 

 the hindwings. The scaling of the males, compared with the 

 females, is noted by Pierce (in litt.) as follows : <? (1) The trans- 

 parent scales, -004 in. x *002 in., yellow in tint, four-lobed at the 

 apex. (2) The dark scales similar in shape ; of a bluish- brown colour. 

 (3) The underside scales -006 in. x *005 in., with four points. (4) The 

 androconia -002 in. x*0015 in., almost square at the apex ; striated 

 with eleven or twelve stripes, each composed of about five spots, the 

 remainder of the stripes coalescing into lines towards the base of. the 

 scales. 2 '• (1) The transparent scales, -004 in. x '003 in., yellow 

 in tint, many being six-lobed. (2) The dark scales, -004 in. x -0035 in., 

 four-lobed. (3) The black apical and marginal scales of the forewing, 

 •005 in. x "0015 in. ; this area is without the yellow scales. (4) The 

 underside scales, similar to those of $ with five points. Aurivillius 

 notes (Bidr. Svensk. Ak. HandL, v., pp. 22-23) that, in the $ , there 

 are certain scales ("bladder-scales"), a little longer than broad, almost 

 square in outline, with quite straight sides, and a slightly convex point. 

 There are nearly thirteen rows of these scales. If an uninjured wing- 

 be examined under the microscope, one can see how the apices of these 

 scales protrude between the rows of the large wing-scales, being very 

 pale, transparent, and unpigmented. One at once notices also, in 

 the wing-membrane, a distinct difference in the $ and $ , for the 

 points of attachment of these scales form distinct rows in the intervals 

 between the rows of wing-scales, a row in each. They do not, gener- 

 ally, occur in the middle of the interval, but nearer to its outer 

 margin. The discs are distinctly different from those of the ordinary 

 wing-scales, being thicker and apparently swollen. Scudder 

 notes (Butts. New Engl., ii., p. 934) that the androconia are 

 scattered, without definite position, over the upper surface of the 

 wings ; these have slightly divergent sides, so that the regularly 

 covered apex is nearly half as broad again as the sloping base ; 

 they are slightly longer than broad, and furnished with about ten 

 parallel rows of exceptionally large bead-like spots, which are confluent 

 in the basal half of each row ; the stem tapers throughout, is almost 

 half as long as the lamina, and gradually expands to it. The extreme 

 length of the lamina is about -0075mm., these being much smaller 

 scales. He adds (op. cit., p. 946) that, "the androconia, of the form 

 lucia at least, are undoubtedly scent-scales ; for, when the finger is 



