THE TRAGTJLID^. 383 



and metatarsals of tlie third and fourth digits unite very 

 late, or, as in one genus, Hyoemoschus, not at all. The 

 canines are well developed in both jaws, and the premolar 

 teeth are sharp and cutting. 



The oesophagus opens at the junction of the mmen with 

 the reticulum, the communication between the two being 

 very wide (Fig. i02 B). The epithelium of the rumen is papil- 

 late, and there are two (esophageal folds, as in ordinary 

 Ruminants, but the psalterium is represented only by a very 

 short and naiTow tiibe, the lining membrane of which is 

 devoid of folds. 



The surface of the hemispheres of the brain has fewer 

 convolutions than in any other Ruminants, though this may 

 veiy possibly be connected with the small size of the 

 animal; as it is a general rule that, within the same group, 

 the brain is less convoluted in small than in large animals. 



The blood coi-puscles, small in aU Bwminantia, are 

 remarkably miniite in the Tragulidce, not exceeding xoooo 

 of an inch in diameter. They have circidar contours. 



The placenta is very nearly diffuse,th.e foetal villi being scat- 

 tered over the chorion in bands, not collected into cotyledons. 



As further remarkable peculiarities of this group may 

 be mentioned the ankylosis of the malleolar bone with the 

 tibia, and the tendency to ossification in the pelvic liga- 

 ments and of the aponeurosis of the muscles of the back, 

 ia adult males. Finally, the navicular, cuboid, and ecto- 

 cuneiform bones in the tarsus are all ankylosed together. 

 If, as is probable, Xixuliodon is one of the Tragulidce, the 

 group has existed since the eocene epoch. 



h. The Cotylophora are, like the preceding group, imguli- 

 grade, but the outer metacai-pals aud metatarsals are in- 

 complete at their proximal ends, and the middle ones are 

 early ankylosed into a cannon bone. The malleolar bone is 

 always distinct. The navicular and the cuboid bones of 

 the tarsus are ankylosed together, but rarely with any other 

 tarsal bone. The premaxilla is devoid of teeth in the adult. 

 The stomach has the structure which has been described as 

 tyjiical. 



