No other breeds have been so extensively diffused in the United States, within comparatively so brief a period, as the Berkshires, and they have produced a marked improvement in many of our former races. They weigh variously, from two hundred and fifty to four hundred pounds net, at sixteen months, according to their food and style of breeding; and some full-grown have dressed to more than eight hundred pounds. They particularly excel in their hams, which are round, full, and heavy, and contain a large proportion of lean, tender, and juicy meat, of the best flavor. None of our improved breeds afford long, coarse hair or bristles; and it is a gratifying evidence of our decided improvement in this department of domestic animals, that our brush-makers are obliged to import most of what they use from Russia and northern Europe. This improvement is manifest not only in the hair, but in the skin, which is soft and mellow to the touch; in the finer bones, shorter head, upright ears, dishing face, delicate muzzle, and wild eye; and in the short legs, low flanks, deep and wide chest, broad back, and early maturity. THE NATURAL HISTORY OF THE HOG. [Illustration: SKELETON OF THE HOG AS COVERED BY THE MUSCLES. 1. The lower jaw. 2. The teeth. 3. The nasal bones. 4. The upper jaw. 5. The frontal bone. 6. The orbit or socket of the eye. 7. The occipital bone. 8. The first vertebræ of the neck. 9. The vertebræ of the neck. 10. The vertebræ of the back. 11. The vertebræ of the loins. 12. The bones of the tail. 13, 14. The true and false ribs. 15. The shoulder-blade. 16. The round shoulder-bone 17. The breast-bone. 18. The elbow. 19. The bone of the fore-arm. 20. The navicular bone. 21. The first and second bones of the foot. 22. The bones of the hoof. 23. The haunch bones. 24. The thigh bone. 25. The stifle bone. 26. The upper bone of the leg. 27. The hock bones. 28. The navicular bone. 29. The first digits of the foot. 30. The second digits of the foot.] DIVISION. _Vertebrata_--possessing a back-bone. CLASS. _Mammalia_--such as give suck. ORDER. _Pachydermata_--thick-skinned. FAMILY. _Suidæ_--the swine kind. GENUS. _Sus_--the hog. Of this genus there are five varieties. _Sus Scropa_, or Domestic Hog. _Sus Papuensis_, or Bene. _Sus Guineensis_, or Guinea Hog. _Sus Africanus_, or Masked Boar. _Sus Babirussa_, or Babirussa.