The skulls of most of the swine family may be recognised by the long face, and the large size, in both jaws, of their dog-teeth or tusks. These are especially large in the male sex, and are often curiously curved, those of the upper jaw upwards, and those of the lower outwards and upwards. The incisor, or biting, teeth vary very much in different species and at different ages. They are often shed early, especially those of the upper jaw. In some pigs the lower incisors are strong and slope directly forwards, as if for digging. The incisor teeth are of less service in the pig than in most animals, and are only exceptionally used for biting or grazing. The pig makes great use of the snout, and the nasal bones are strong and prominent. The molar teeth are well adapted for chewing, and are usually worn flat on their surfaces. Pigs champ but do not ruminate. They are, for the most part, root-eaters. The rim of the orbit is always imperfect. The normal dentition is three incisors, one canine, and seven molars in each jaw. If the upper canine is extracted the lower one will grow into a complete circle and reach the gum close to the root of the tooth. When thus curved it forms an ornament much valued in Fiji. SKULL OF THE BABIRUSSA. Note especially that the tusk of the upper jaw grows upward from the first. No part of it is directed into the mouth. This tusk is of extraordinary size, and it curves upwards so as to touch, and sometimes even to pierce, the skull. They are, as compared with those of other swine, slender tusks, more especially the under ones. The upper tusk grows through the skin of the upper lip. In old animals, when it is well curved, it must be useless as a weapon. It may serve to protect the eyes when the animal rushes through brushwood. In the female the tusks are small. * * * * * ANSWERS TO CORRESPONDENTS, &c. CONCHOLOGIST.--Your shells are _Helix nemoralis_ (immature), _Hyalinia (Vitrea) pura_, and _Buliminus obscurus_. _Vitrea pura_ is a much smaller shell than _V. nitidula_, the latter may be distinguished from _V. radiatula_ by the striæ not being continued from whorl to whorl. _B. obscurus_ is much smaller than any member of the genus _Clausilia_. If you examine in May the trunks of beech trees growing on calcareous soils you will find _B. obscurus_ and _Clausilia laminata_ ascending them in large numbers to spend the summer aloft, coming down again in October to go into hybernation at the base of the trees during the winter months. You will find _C. rugosa_ (in modern terminology, _C. bidentata_) equally common on the trees, it is smaller and thinner than _C. laminata_. _B. obscurus_ is a short, stout little shell, seldom exceeding 9 millimetres in height.