446 DE. H. W, MAEETT TIMS ON" THE 



(i.) Whether of the upper cheek-teeth, pm-* or m^ more 

 nearly approximates to the type tooth, and is therefore 

 safest for the comparison of known forms ? 



(ii.) Is there a diverse modification of the teeth for opposite 

 ends of the jaw ? 



(iii.) Is the Milk or the Permanent dentition the more 

 primitive ? 



(iv.) Is Otocyon primitive in the number and characters of 



its teeth ? 

 To these questions I have endeavoured to give an answer. 



The general character of the teeth of the Common Dog are 

 known to all, and a brief description of these characters is to be 

 found in most test-books of Comparative Anatomy ; but, so far 

 as I am aware, no detailed description of the individual teeth in 

 this and other members of the same family has as yet been given. 



In 1880 the late Professor Huxley published (7j his well-known 

 monograph " On the Cranial and Dental Characters of the 

 Canidse." In this paper a classification of the Dogs was pro- 

 posed, based largely upon certain dental characters, especially 

 size in relation to the basi-cranial axis. He did not touch upon 

 the characters of the individual teeth which bear upon the 

 homologies and inter-relationships of the cusps. 



I propose therefore, in the first instance, to give a detailed 

 description of the Milk and Permanent teeth of the Dog. In 

 doing so, I shall employ Osborn's terms, but I shall do so merely 

 as a matter of convenience and not as implying that I thereby 

 accept the Tritubercular theory which he upholds. 



Metliod. — The jaws of animals varying in age from about the 

 seventh week of intra-uterine life up to three months were 

 examined. After being thoroughly dehydrated and clarified in 

 oil of cloves, one side of the jaw was dissected off and the teeth 

 examined in situ. The younger specimens were also examined 

 microscopically. The jaws were decalcified in a 1-per-cent. solu- 

 tion of chromic and hydrochloric acids. After staining in 

 borax-carmine, serial sections were cut and models made in wax 

 of some of the developing teeth. 



Description of the Milk-teeth. — The dental formula of the 



q q 1 1 q q 



deciduous teeth is i. - — -, c. - — -;, m. =— ?=28. The order and 



