Our next genus contains only two British species. The first of these--the Large Copper--was once a common insect at Whittlesea in Cambridgeshire, and in some of the fens of Huntingdonshire, but is now feared to be quite extinct, as none have been seen for many years. The last capture was made in 1847 in Huntingdonshire. However, it _may_ turn up again; and even if it does not, it would be a pity to allow the memory of so fine an insect to die out; so we find room to figure it (Plate VI, fig. 8), and append a few remarks. There is a very great difference between the male and the female. The former is of a brilliant copper hue, and all the wings have a black margin and a black streak near the middle. The female is larger; and the coppery colour is much redder. The black border of the fore wings is wider, and there are also several large black spots on these wings. The hind wings are almost entirely covered with black, with the exception of a broad coppery band near the hind margin. The food plant of the caterpillar appears to have been the water dock (_Rumex Hydrolapathum_), on which the eggs were laid late in the summer. It is probable that the caterpillar was a hybernator, seeking its winter shelter while still very young; and it was full fed in June. Its colour was green, with a darker stripe of the same colour on the back; and the chrysalis was attached by anal hooks and a cord round the body. _The Small Copper_ (_Polyommatus Phlaeas_) The only other British member of the genus _Polyommatus_--the Small Copper--is one of the commonest of our butterflies. It may be found in nearly all parts of the British Isles from April to September, more particularly in April, June, _and_ August, for it is apparently triple brooded. This brilliant and lively little insect is shown on Plate VI (fig. 9), and, being so very familiar, needs no description. The caterpillar feeds on different species of dock--the broad-leaved dock (_Rumex obtusifolius_), the fiddle dock (_R. pulcher_), the sorrel (_R. acetosa_), and the sheep sorrel (_R. acetosella_); also on the ragwort (_Senecio Jacobaea_). It is full fed about three weeks after hatching, and then changes to a small and stout chrysalis, of a pale brown colour, on the leaf of its food plant. The caterpillar itself is green, with a reddish line on the back and on each side; and it glides over the surface of the leaves something after the manner of a slug, without exhibiting any very apparent motion of its short legs and claspers. _The Tailed Blue_ (_Lycaena Baetica_) We now come to a genus containing no less than ten species of beautiful little butterflies, known commonly as the 'Blues;' but one of them exhibits no trace of the colour so characteristic of the group, although it resembles the others in structure and habits.