306 APPENDIX. 



Concerning this interesting case Dr. Robert Fairchild, in a letter of 

 August 30, 1892, says: " Yours of 28th received, and in reply can 

 only say the age of the horse with long molar was 12 years. I had 

 to extract four and cut down the others. It was caused by grinding 

 on one side, and after it got to going, and not being floated off. 

 could not get back. The growth of teeth varies. Some have good 

 molars at 30; but I have seen a horse 15 years old without any 

 molars, having a prematurely old mouth. I find the teeth depend a 

 great deal on what the horse is fed on. The harder the substance 

 the harder the teeth, and the longer they last. All teeth continue 

 to grow (but not as fast after 15) until old age, or become diseased. 

 If one gets broken off or diseased, the opposite grows up faster, as 

 there is no opposition to wear it away." 



DECIDUOUS CANINE TEETH. 



LIKE the remnant (wolf) teeth and the permanent canines, the 

 deciduous canines are doubtless gradually becoming extinct. The 

 fact that the ancients describe them and that some veterinarians of 

 the present day question their existence, seems to sustain this the- 

 ory. Columella says: " Others grow again in the fourth year, after 

 those that are called canine or eye-teeth have fallen off." Palladius 

 says: "At 4 years their canines change." (See pages 294, 295.) 



The teeth are well illustrated on page 52 of this work. Dr. Sayre 

 says : " I have often seen them in colts from 4 to 8 months old." 

 Dr. Hinebanch says (" Veterinary Dental Surgery," p. 35): " They 

 are small and occupy the position that is eventually taken by the 

 permanent canines. I have invariably found them present in both 

 colts and fillies, when preparing heads for anatomical specimens, 

 provided the animals did not exceed six weeks of age. Up to that 

 time they are thoroughly imbedded in the bones." Dr. Hinebauch 

 sends me a 6-days-old colt's canine. It is a quarter inch in length. 



EVOLUTION ILLUSTRATED BY THE SPLINT BONES. 



DR. J. M. HEARD says : " In the evolutiom of the horse from 3 

 toes to 1, the side toes have gradually become united to the center 

 toe. The transformation to the 1-toed animal is not even yet com- 

 plete, for the young horse has a respectable reamant of the lateral 

 toes still in existence. This is true also of fetal life. But it may be 

 asserted that the horse is fast arriving at the stage when there will 

 be no separate splint bones," &c. (See Figs. 3 and 4, page 265.) 



