246 VOCABUlAKY. 



is very rank and somewhat musky. It ranges from Siberia 

 to Tonquin. Johnson's N. U. Cyc. 



MUNTJAC, of India, Java, &c., a small deer, but little over two 

 feet high. The males have small horns; the females are 

 hornless. Their flesh is excellent. The Chinese muntjac, 

 like the preceding, is often half domesticated, and is some- 

 times bred in European parks. Johnson's N. JT. Cyc. 



MYL'ODON. An extinct edentate animal, allied to the megathe- 

 rium. Lyell. 

 N. 



NAR'WHAL, or SEA-UNICORN. It is most nearly related to the 

 white whale. Belonging to an order in which many of the 

 members never develop teeth at all, it, of all animals, is sup- 

 plied with a tooth altogether out of proportion to its size, and 

 it is, moreover, developed in utter contravention of the rules 

 of bi lateral symmetry, which in every known case among 

 vertebrates govern the production of the teeth. In both 

 sexes the lower jaw is edentulous. The male, however, is 

 provided, on the left side of the upper jaw, with a tusk from 

 eight to ten feet long. It is straight, spirally grooved ex- 

 ternally, and hollowed within into a persistent pulp-cavity. 

 On the right side the corresponding tooth generally remains 

 hidden, smooth, and solid, within the jaw. In addition to 

 these, there are two small rudimentary molars concealed in 

 the upper jaw. The narwhal, which is considered one of 

 the greatest curiosities of natural history, attains to a length 

 of fifteen feet. Its single spiracle or blow-hole is situated on 

 the top of the head. E. C. H. Day. 



NECRO'SIS, or death of a bone, corresponds to mortification of 

 the soft structures, and is as distinct from caries as mortifica- 

 tion is from ulceration. Necrosis is divided into four varie- 

 ties, namely: 1. The scrofulous. 2. The superficial, or that 

 which involves the outer lamellae, and presents itself in the 

 flat and long bones. 3. That form which destroys the in- 

 ternal part of a bone, and in which the outer shell is not af- 

 fected. 4. That in which the whole thickness of the bone 

 dies. W. Williams. 



O. 



ODONTAL'GIA. Toothache. 



Generation or mode of development of the teeth. 



