"Eyes glabrous. Club of antennæ abrupt." (Plate [I]., figs. 25, 26, and 27 neuration of Erebia pluto.)
"An extensive and essentially Alpine genus inhabiting the mountains of Europe, Asia, North America, and South Africa. Pupa unattached amongst stem bases of grass."—(Meyrick.)
We have two species in New Zealand.
EREBIA PLUTO, Fereday.
(Erebia pluto, Fereday. Erebia merula, Hewitson, Ent. Mo. Mag. xii. 10 (1874). Oreina othello, Fereday, Trans. N. Z. Inst. viii. 302, 304, pl. ix. (1876). Percnodaimon pluto, Butl., Ent. Mo. Mag. xii. 153 (1876); Catalogue of N. Z. Butterflies, 10.)
(Plate [XI]., fig. 8 ♂, 9 ♀, 10 under side.)
This fine butterfly has occurred plentifully on many mountain-tops in the South Island, from Nelson to Lake Wakatipu. It has never been observed in the North Island.
The expansion of the wings of the male is 1¾ inches, of the female 2 inches. On the upper side all the wings are a very rich bronzy-black. The fore-wings have a paler patch near the apex, containing two small, and three large black ocelli with white centres; these ocelli are usually joined together. On the under side all the wings are considerably paler and greyer. The hind-wings have a series of pale spots near the termen, and a paler shade across the middle.
The insect varies chiefly in the number of ocelli. On the upper side of the fore-wings there are sometimes only four, the minute ocellus on the costa being absent, whilst occasionally a small extra ocellus appears below the normal series. On the under side this last-mentioned ocellus is very frequently, but not invariably, present. In some female specimens an extremely minute ocellus may be detected on the upper surface of the hind-wings near the termen. On the under side of the hind-wings in both sexes the series of pale terminal spots are often absent, and the general depth of the colouring varies considerably.
Mr. Fereday has described and figured a very interesting variation occurring in the structure of the costal veins of this species,[[54]] vein 11 of the fore-wings sometimes running into 12 (see Plate [I]., fig. 26), and sometimes being entirely absent (fig. 25). After reading Mr. Fereday's article I examined the specimens in my own collection, and found that all those taken on Mount Arthur and on Mount Peel, in the Nelson district, had veins 11 and 12 joined, whilst the two specimens I took on Mount Enys, Castle Hill, West Coast Road, had vein 11 absent. As, however, Mr. Fereday has specimens exhibiting both forms of neuration, from Castle Hill and from Mount Hutt, I do not think it likely that the peculiarity is confined to butterflies from any particular locality. Like Mr. Fereday, I have observed that the specimens having veins 11 and 12 joined, are smaller than those having vein 11 absent.