PLEBEIUS ARGUS. 173 



var. cretaceus. (2) The heath race rather smaller, the J s with fairly 

 well-defined marginal border, the underside distinctly darker; the ? s 

 scarcely ever shaded with blue = argi(s, Linn.* (3) The moorland 

 form rather smaller than the chalkhill form, the $ s with narrow 

 marginal borders, the underside pale ; the 2 s exceedingly strongly 

 shaded with blue = var. masseyi. Throughout these races, there is a 

 considerable amount of variation in the colour-tint of the $ s. The 

 most common form is a bright purple-blue = ab. purpurascens, n. ab., 

 occasionally this is intensified into a brilliant violet-blue = ab. caerideus, 

 n. ab., sometimes it is weakened off into a lilac or lavender-blue — ab. 

 lilacina, n. ab., and in its extreme form to a lilac that is almost 

 pinkish in tone = ab. pallida, n. ab. We have such a form from 

 Dover, and Prideaux another from Berisal, and Barrett notes 

 that, in the " Webb coll.," is a $ of a pale lavender colour, and others 

 with white dashes extending from the borders. Walker notes a 

 "small, pale lavender-blue $ from Dover," in the "Dale coll." Dwarf 

 $ specimens appear always to develop a pale lavender ground colour. 

 Our tiniest example 18-5mm. from "Pontresina, July 10th, 1904," is of 

 the palest lilac tint; very similar specimens in the British Museum coll., 

 are labelled " Lapland, Leech coll.," a $ (19*5mm.) and $ (22mm.), 

 the former with good border and discoidal lunules; the orange lunules 

 on hindwings of 2 fairly-developed, on forewings almost absent. 

 Two other little lavender $ s (20mm. and 24mm.), but with narrower 

 border, and two almost similar small 2 s (22-5mm. and 23mm.), but 

 with a little more orange, are ticketed " Roman Campagna, 3. ix. '44, 

 Zell. coll." One suspects a similar cause for the likeness in all these, 

 viz., a short larval life on innutritions food, that from Pontresina being 

 badly placed, those from Lapland, owing to the short summer and 

 limited feeding-period, the Italian examples through having to feed up 

 on parched food in the August heat, having hatched at the wrong 

 period of the year. These tiny examples, of 21mm. or less, we call ab. 

 minutissimus, n. ab. Cox notes that, in mid- June, 1868, the species 

 occurred near Tunbridge in thousands, and one specimen captured 

 measured only 18mm., the spots on the underside being very faint, 

 and reminding one somewhat of those of Cupido minimus. Usually, very 

 small specimens have the underside spots well-developed ; in this 

 respect they do not fail. As showing the difference in average size of 

 the British races, we note that Buckstone exhibited (Proc. Sth. Loud. 

 Ent. Soc.f 1899, p. 109) a comparative series of specimens from 

 Oxshott, on gravel soil, and another series from near Sevenoaks, on 

 chalk soil, those from the chalk averaging very much larger than those 

 from gravel. As between the imagines of the great plain of Central 

 Europe, and the Alps, a distinct difference is observable ; those from 

 the plains are larger, brighter, bluer (more violet), with narrow margin 

 to forewings, and spotted hindwings, and with rather pale undersides, 

 and very similar whether from the hotter valleys of Switzerland, theplains 



* There is much to be said for considering this the Linnean type form, since 

 (1) the j specimen in the Linnean collection carrying Linne's own label is of this 

 form (see anted, p. 167), and (2) the ? which Linne labelled and described as 

 "idas" (Fn. Suec, 2nd ed., p. 284), appears also to belong here; this is sup- 

 ported by the fact that in his description of Idas (see anted, p. 168) Linne adds 

 "Habitat in ericetis," thus settling the fact that his ? , at any rate, was taken "on 

 heaths," as the c? certainly appears to have been. 



