1857.] 



OWEN DICHODON CUSPIDATUS. 



195 



In these the last true molar cuts the gum before any of the pre- 

 molars appear, and the canine teeth ('corner-nippers' of the Vete- 

 rinarians) are the last of the permanent teeth to come into place, 

 their appearance marking the completion of the third year in the 

 Sheep, and a somewhat later period in the Ox, In the Hog the 

 canines appear before the premolars, and these are in place and use 

 before the last molar is on a level with the rest of the grinders. 



In the Bichodon cuspidatus the second true molar, in the upper 

 jaw, is in place before any of the deciduous series of teeth have been 

 shed ; and it is coming into place, with the crown complete, before 

 the pulps of the premolars have even begun to be calcified. The 

 lower jaw of the Sheep at from nine to twelve months would afford 

 the nearest parallel amongst existing Artiodactyles to that of the 

 imxndlMre Bichodon figured in pi. 4. fig. 2. vol. iv. of the 'Quarterly 

 Journal of the Geological Society.' But by the time the second true 

 molar in the Sheep is as far advanced in development as in the Bicho- 

 don (fig. 2, loc. cit.,p 2, upper jaw), the first permanent incisor is in 

 place, and the germs of the premolars in the cavities of reserve have 

 calcified crowns. 



I append the subjoined Table, indicating the several teeth by the 

 symbols explained in my Paper on the Homologies of the Teeth*, and 

 in the Article Teeth of the 'Cyclopaedia of Anatomy and Physio- 

 logy,' vol. iv. 



The necessity of exactness in the records of the age of the valuable 

 breeds of domesticated cattle, exhibited in competition at Agricul- 

 tural Meetings, has led to a greater accuracy in the statements of the 

 periods of development of the different teeth in the Ox, Sheep, and 

 Hog, and I have combmed the results of my own observations with 

 those recorded by Bojanus, the learned Veterinary Professor at Wilna, 

 and by Mr. Simonds, the Professor of Cattle Pathology in the Royal 

 Veterinary College of Loudon f, in the following 



Table of the Times of Appearance of the Permanent 



Teeth in the 

 I Ox. Sheep. Hog. 



Symbols. 



i 1 



i2 



i3 

 c 

 m 1 

 m2 

 m 3 

 dorp 1 

 p2 i 

 p3 I 

 pA 



Earlv. 



Late. 



Year. Month. Year. Month. 



Earlv. 



Late. 



Year. Month. Year. Month. 







4 to 8 



to 4 



9 to 12 



6 



6 















6 



6 



Year. Month. 





 6 

 9 

 9 

 6 



10 

 6 

 G 

 

 



1 d 



VOL. 



* Philosophical Transactions, 1850, p. 481. 

 t "The Age of the Ox, Sheep, and Pig," 8vo, 1854. 

 XIII. — part I. P 



