Note on a Diastema between Molars and Premolars 



in an Ox. 



By 



Richard J. Anderson, 



G al way. 



(Witli 1 Fig.) 



The lower jaw of an ox, that has been nsed for demonstrating the 

 dentition, presents an Anomal}^ that is somewhat rare, if not in actual, 

 at least, in its marked character. 



The Central Incisors have nearly square crowns, so have the 

 next pair. The third pair are wider anteriorly and the Corner teeth 

 are broader from side to side, than from before backwards, all touch 

 at the crowns except the right corners, which are four and a quarter 

 inches from the first premolars. 



The premolar range measures two inches from before back (f .f 

 a I Inch.). The Molar range three and three eighths inches, 1. seven; 

 2. eight; 3. thirteen eighths of an inch. 



The Diastema is one and an eighth inches deep five eighths of 

 an inch broad at the middle. A little less above and below. 



The crescentic margin that bounds the fossa leading to the gap 

 is an inch external by and three eighths of an inch internally. 



The times of emergence of the Incisors (permanent) may be put 

 down as follows. Central (Pincers) 18 to 20 months. Second (1^* Inter- 

 mediate) at 26 to 30 Months. Third (2"^^ intermediate) at 36 to 42 

 Months. Fourth (Corners) at 31/2 years to 4^2 years. Premolar I: 

 2^/., years; II: 1^/., years; III: 3 years. Molar I: 17.2 years; II: 3 years; 

 III: 4 years. The third Premolar therefore appears above the gum 

 eighteen months later than its two neighbours. In the specimen in 



