84 MK. E. T. NEWTON ON [Feb. I903. 



which extends to the base of the enamel ; this last-named character 

 at once distinguishing this fourth premolar from that of Cervus 

 giganteus. The greater height of the crown of this tooth causes 

 the edge of its alveolus to be pressed down below the level of those 

 of the true molars, and results in an uneven alveolar margin, which 

 is rendered more obvious by the base of the anterior premolar 

 being somewhat above the line of the true molars. Another 

 character of the hindermost premolar is seen in the pattern of the 

 grinding-surface ; two deep sulci extend obliquely quite across the 

 tooth, from behind forward and outward, dividing the surface of 

 the crown into three unequal portions. When a little more worn, 

 the anterior and larger sulcus would become closed in front; indeed, 

 this closure has taken place in the corresponding tooth of the right 

 ramus. The extension of the oblique sulci quite across the tooth 

 is unlike what is found in Megaceros, where these sulci are very 

 shallow, and consequently are early cut off from the outside by the 

 wearing of the tooth, giving a very different aspect to the pattern 

 of the grinding-surface. It is worthy of note that this peculiarity 

 of the fourth premolar agrees very closely with what is found in 

 the corresponding tooth of the reindeer. 



Another peculiarity of the elk's teeth is the extreme obliquity 

 of the crescents as seen on the grinding-surface : this character is 

 well shown in the lower jaw of the Staines specimen. The inner 

 and hinder part of each crescent projects inward much beyond the 

 anterior part of the crescent next behind it, thus giving a strongly 

 serrated edge to the inner surface of the lower cheek-teeth. In the 

 Irish Megaceros this obliquity of the crescent is much less, and 

 the serration nothing like so prominent. 



Besides the differences above mentioned, the lower-jaw ramus of 

 Megaceros differs from the Staines specimen and the recent elk 

 in being much thicker below the cheek-teeth ; in having a less 

 elevated articular and coronoid process ; and in the diastema being 

 much shorter. 



As already stated, there can be no question as to these rami from 

 Staines being referable to the true elk (Alces machlis), and not to 

 the Irish Megaceros {Cervus giganteus). 



Measurements of the Lower Jaw. 



Millimetres. 



Coronoid process to alveolus of median incisor 490 



Articular condyle to ditto 465 



Angle to ditto 440 



Depth of ramus on inside below hinder end of m. 3 64 



Do. do. do. in front of anterior pm 52 



Thickness of ramus below m. 3 2$ 



Length of alveolar margin of cheek-teeth 165 



Do. three premolars 73 



Do. three molars 95 



Do. grinding-surface of pm. 4 27'5 



D.>. grinding-surface of m. 1 28'0 



Height of enamel-crown, outside pm. 4 250 



Do. do. do. outside m. 1 19*5 



Distar.ce between front pm. and alveolus of outer incisor... 153*0 



