MR. W, B. DAAVKT5TS OiN" RHINOCEROS MEGARHINUS. 



407 



collis, D, is faintly developed, and is mapped off from the external 

 lamina that extends beyond it by a depression. One tooth, but slightly 

 worn, presents the anomaly of the posterior valley being completely 

 insulated by the normal entrance being blocked up by a wall of 

 enamel. 



The external lamina of the third milk molar (Figs. 7, 8) is divided 

 by a deep groove I into two equal areae. Anteriorly it projects 

 slightly beyond the point of juncture, with the anterior collis, D. Tlie 

 anterior valley, A, is smaller and more V-shaped than the posterior, 

 B. Of the three colles the median is the larger, and the first and 

 third equal in size. There is a small cusp, probably accidental, on 

 the anterior edge of the median collis. 



In the fourth milk molar, (Figs. 7, 8) the anterior area, M, is 



