the Teeth of Oxen and Sheep. 293 



adult lower jaws showing stages towards a five-toothed con- 

 dition. Three stages are clearly represented, as follows : — 

 (1) Jaws with ^^2 in place; (2) jaws with ^^72 in place but 

 in process of being pushed out, roots partly absorbed ; 

 (3) jaws with ^^^^^^72 absent, with slight traces of alveolus re- 

 maining, In the six-toothed jaws, i. e. where ^^72 is present, 

 that tooth shows very little, or almost no, trace of wear, even 

 though all the remaining teeth, including ^73 and ^^71, are 

 considerably worn. One pair of jaws shows ^^72 in position, 

 but the adjacent premolar is so crowded against it that the 

 pmr2 is only lightly held in its socket, and when lifted out it 

 is seen that its roots are almost absorbed. 



The possibility of this being a persistent miik-mqlar was 

 considered, but on cutting away the bone below the tooth no 

 successional tooth was found nor was any crypt present, the 

 bone being quite compact. The tooth was then carefully 

 compared with another ^^^2 and with a deciduous molar 

 (m. m.2)> a"d was fouud to agree exactly with the former. 



The left ramus of another lower jaw illustrates the shedding 

 even better, as the anterior root of ^^2 is visible, it having 

 been pushed through the anterior wall of its alveolus. Both 

 the above examples would belong to animals considerably 

 over three years of age"^. 



Evidence of the former presence of j^^;^ in otiier adult 

 lower jaws is furnished by partly obliterated alveoli. Tiie 

 youngest jaw showing the rive-toothed condition is one in 

 which ^^74 has just begun to wear. 



Two of the Glastonbury rive-toothed specimens are of 

 further interest, as showing an abnormal condition in the last 

 true molar (sri). In all true ruminants this tooth is charac- 

 terized by the addition of a third posterior lobe f. Tliis lobe 

 is very small and simple in the gnu, and relatively larger in 

 the Bovidse and Cervidse. In the Glastonbury specimens 

 the third lobe of ^73 is much less developed than in two 

 specimens of the gnu in the Manchester Museum J, it being 

 represented by a slight loop only. The same condition is to 

 be seen in the lower jaws of a polled skull of a " wild " white 

 cow supposed to be the last relic of a herd formerly kept at 



* Calculated from table in Owbu's 'Anatomy of Vertebrates,' vol. iii. 

 1868, p. 352. 



t Tomes, * Dental Anatomy ' (1898, p. 406, footnote), mentions Neo- 

 tragus hemprichii, a small Abyssinian antelope, as having only two lobes 

 to tbe third lower molar. 



X In both these specimens of gnu the lower jaws have only five teeth, 

 ^^72 being absent. 



Ann. & Mag. N. Hist. Ser. 8. Vol. xv. 20 



