PLEKEIIDI. 155 



Latiorina — Latiorina ortitulus (type), L. pyrenaica, etc. 



Agriades— Agriades meleager, A. coridon (type), A. thetis (bellargns), etc. 



Having indicated in this manner the groupings into which 

 the species with which we are most conversant in the field 

 seem to fall, and which appear to be supported by much more 

 abundant material in the British Museum collection, we appealed 

 to Dr. Chapman for information as to how far the genitalic 

 characters would bear out these groupings. He very kindly 

 examined the genitalia of the above-named, and other, species. The 

 information he is able to afford supports, to some extent, our grouping. 

 He notes that " thePlebeiid ' clasp ' varies little throughout the group, 

 and is very unlike that of any other group. It is to be observed, also, 

 that, in most groups, the dorsal armature is most constant, i.e., generic, 

 the clasps the most varied, i.e., specific. In the Plebeiids, the contrary 

 is the case. The Plebeiids have, as their most characteristic feature in 

 the ancillary appendages, a clasp, large, tapering a little to each end, 

 so that in most view r s its outline is fusiform, each clasp quite separate 

 from its fellow, and with the two divisions into wmich the clasp, in not a 

 few Lycamids, is divided, only distinct at the very end. It is further 

 characteristic that this clasp is so uniform throughout the group, that 

 it is only by minute details that one species can be distinguished, in 

 many cases, from another. Yet, so far as I know, this form of clasp 

 does not occur in other families of blues. The dorsal portion of the 

 armature, consists of two lateral portions connected across the actual 

 dorsum by a comparatively narrow and featureless strip of chitin, less 

 reduced, however, than in Gelaatrina. Each side has a rather long 

 process, clothed with hairs, and of by no means simple structure. 

 Attached to the base of this is a smooth hook, so articulated as to 

 have considerable freedom of movement. The base of the hook is 

 more or less swollen, and extends somewhat transversely to the dorsal 

 process, then with a bend which may be a right angle, or even nearly 

 180°, the rest of the hook extends more or less parallel to the dorsal 

 process on its dorsal s«ide. It is the size and form of this hook, and 

 its relation to the dorsal process, that affords the easiest characters to 

 seize for the subdivision of the Plebeiidi. In favour of the subdivision of 

 this large group into separate genera, as proposed by Mr. Tutt, I may 

 note, as I have occasionally remarked in previous studies, that the 

 dorsal armature affords the generic characters, the clasps the specific. 

 If we were to retain Plebeius as a genus to include all the species, this 

 would not be so, the clasp, in that case, being unquestionably the 

 generic character. By dividing the group into several genera, we are 

 forced to use the dorsal armature for the generic character, rather than 

 the clasps, and revert to the latter for specific ones. This is, of course, 

 a very general statement, and neglects various individual exceptions. 

 The following points on the groups indicated, may prove of interest: — 



Plebeius : We are met, at the outset, with a question of some difficulty. 

 Plebeius has, it appears, as type, argus, Linn, (aegcrn, Schiff .) . With this has always been 

 associated argyrognomon, Bergstr., and the. difficulty has usually been regarded in 

 respect of these two species, not how to unite them generically, but how to separate 

 them even specifically. When we examine the ancillary appendages, we find that 

 these two species differ from each other more decidedly than do almost any other 

 two species of Plebeiids, and in so differing they are also easily distinguishable 

 from all other Plebeiids (with which I am familiar). To retain them in the same 

 genus, we must assume that they left the central forms together, and since 



