Digestive System Special. 83 



In tlie common Dolphin the number of teeth amounts to 190; the maximum 

 number in the Class Mammalia. 



Sirenia^ are Diphyodonts*, and have teeth of different kinds, 

 Incisors and Molars. In Halicore (Dugong) the superior Incisors alone 

 project in the male, and in the female neither upper nor lower 

 Incisors are visible. The Molars have flattened or ridged crowns 

 adapted for vegetable food. Those of Halicore consist of a large 

 body of dentine, a small central part of osteo-dentine, and a thick 

 external investment of Cement; Enamel is absent. In Manatus 

 Molars are present in both jaws. In Halicore abortive teeth alone 

 are found in the deflected portion of the lower jaw. 



InSnamellata. This Order includes two genera, which are de- 

 void of teeth, Myrmecophaga and Manis ; the rest are possessed of 

 those organs. The Bradypodidae generate only one set ; they are, 

 therefore, Monophyodont. The Dasypodidse probably all generate 

 two sets, and are therefore Diphyodont. The teeth are very rarely 

 implanted in the intermaxillary bones. No true enamel is present on 

 any tooth (hence the name here given to this Order). The teeth 

 are of uninterrupted growth, and are concomitantly implanted by 

 a simple, undivided, and generallj' deeply excavated base. 



The teeth of the Dasypodida3 (Armadillos) are harder than those of other 

 species of Inenamellata : those of Orycteropus are continued solid, and of the 

 same dimensions, to the bottom of the socket ; where they terminate in a tnm- 

 cate undivided base, and may be looked upon as an aggregate of small denticles. 

 D. Sexcinctus has the anterior tooth, which is shaped like the succeeding Molar, 

 implanted in the Intermaxillary bone. Of the eight teeth habitually found in 

 each side of the mouth of the nine-banded Armadillo, both in Maxilla and Man- 

 dible, all except the most posterior in each set are preceded by well-developed 

 functional milk teeth, which closely resemble the permanent teeth in form, and 

 nearly equal them in size, and are not shed until the animal has almost attained 

 its full developmentf. An example of excessive number of teeth occurs in this 

 family in the Priodont Armadillo, which has ninety -eight teeth. In the Brady- 



5 5 

 podidse the teeth seldom exceed ^ in number ; of these the anterior one on 



each side is generally much prolonged. 



Marswpialia. Replacement. The animals of this Order present 

 a peculiar condition of dental succession, uniform throughout the 

 Order, and distinct from that of all other Mammalia. This peculi- 



* Cf. infra. Marsupialia, Replacement. 



r Flower. Journal of Anat. and Phys. 1860. 



