BRITISH REPTILES
commons, woods, hillsides, grassy and sandy banks, heaths, rides, quarries, etc. A chalky soil appears to be a favourite retreat, yet, curiously enough, we have rarely met with this species on our own Chalky Chilterns in Northern Hertfordshire. The average number of young is given as 13 , though less and much larger figures have been stated. I knew of a dam Adder in Sussex which was accompanied by a family party of 16. The young are born in late Summer or early Autumn, this being a viviparous species. The usual dietary consists of ant-pupæ (often erroneously referred to as ant-eggs), birds and their eggs, insects, lizards, mice, moles, and slow worms. Newts, young rats, and even water-voles, have also been known to be taken. Adders vary a great deal in colour, and my old friend Professor Gerald R. Leighton has no hesitation in stating that they vary from black to white! He gives as a general description of the body-colours those of deep and pale blue, mottled-grey, orange, and yellow. The black, brown, or warmer colour marking on the head, and along the back, is not subject to such variation as the body-colourings. By these dark markings the Adder may at once be distinguished from other Snakes on the British list, and especially by the curious V-shape mark on the crown of the head. The average length of an adult is 20 to 25 inches. Female preponderate (it is said in the proportions of as many as three or four to one), but Vipera berus is for the most part a shy, if not nervous creature, and will do all that is possible to glide out of harm's way if danger
