AND THEIR TRANSFORMATIONS. 09 



Caterpillars of such species as liave been observed feed upon leguminosc herbs, such as Trifolium, Lotus, 

 Onobrycliis, Medicago, &c. 



From the generic synonymes given above, it will be seen that the French, German, and English schools of 

 Entomology are at variance as to the name to be given to these insects. If in this instance I have follov^ed the 

 authors of our own conntry, it is, first, because Latreillo himself, the founder of the genus, has in his later works 

 given one of the Blues as its type ; secondly, becanse the name is a very expressive one ; and thirdly, because the 

 objections to the use of either of the names of Argus or Lyctcna for the present group are as strong as those 

 against the employment of tiiat of Polyommatus. 



The number of the species in the genus being considerable, Ochsenheimer divided it artificially into two 

 sections, according to the presence or want of a row of fulvous spots within the hind margin of the posterior 

 wings beneath. Subsequently Sir. Stephens observed that " P. Argiolus differs from its indigenous congeners by 

 the form and texture of its wings ; that P. Alsus, Agestis, and Artaxerxes arc characterised by a uniformity of 

 colouring in both sexes; while the remaining species are distinguished in general by the males being blue above, 

 and the females brown, excepting Po. Arion and Alcon, in which the latter sex is known by a predominance of 

 brown above, and by having the disk considerably spotted with dusky or black, and that the five first species 

 (Argiolus, Alsus, Acis, Arion, and Alcon) are destitute of a marginal fascia beneath, which is, however, 

 rudimentary in the two last-mentioned insects. Again, some few of the species have the eyes pubescent, while 

 others have them naked." (Illustr. B. Ent. Haust. 1. p. 85.) 



Dr. Horsfield, in the " Lepidoptera Javanica," divided the genus Polyommatus into two sul>gcncra, the first 

 named Pithecops, from the peculiar aspect of the chrysalis, distinguished by a very distinct habit and aspect, 

 " owino' to the great length and lateral expansion of the wings, to their comparative narrowiwss, and to their 

 (especially the posterior pair) being regularly elliptical and rounded in the anal region." Tliis subgenus is 

 represented in the European Fauna by P. Alsus, and several others described by Ochsenheimer, having the 

 character " ate integerriniEe." Tlie subgenus Polyommatus, properly so called, is characterised by Dr. Horsfield 

 by having the margins of the hinder wings with the anal extremity angular, and produced to a short, rounded 

 point. Mr. Stephens, in his subsequently published Catalogue, adopts these two subgenera as sections, giving 

 Argiolus and Alsus, as well as Acis, as belonging to Pithecops ; and in his manuscripts, which he has been so kiud 

 as to allow me to examine, he confines Pithecops to Argiolus, giving Alsus, Acis, Arion, and Alcon under the 

 sectional name of Nomiades, and the remainder under that of Agriades, from Hiibner. As, however. Dr. 

 Horsfield gives Alsus expressly as the European typo of Pithecops, which he characterises by the comparative 

 narrowness of the wings, and as Argiolus has broader wings than any other European species, we must restrict 

 Pithecops to P. Alsus, which species, indeed, possesses a peculiarity in the arrangement of the veins of the fore 

 wings which has not hitherto been noticed, and which I have found in no other Lcpidopterous insect, tlius 

 confirming Dr. Horsfield's views. As, however, in treating on the genus Thecla, I did not consider it advisable 

 to separate T. Rubi, although difiering from the other species in the veins of the wings, so I shall not in the 

 present genus separate Alsus generically from the rest, considering them too closely allied together to allow of 

 such a step. J\ly arrangement of the species is therefore as follows : — 



Section I.— (Pithecops, Horsfield.) First branch of the post or subcostal vein of the fore wings coalescing with 

 the mediastinal or costal one, and subsequently again brandling oiF from it. P. Alsus. 



