92 MK. G. BUSK ON THE ANCIENT OR 



and 2"-2 in the transverse (l"-8 X 2"-2) taken at the base of the crown. The extreme 

 height of the crown in its present state is 2""5 ; and it probably never exceeded 2"-6 

 when quite unworn. 



On the dorsal or outer surface the second, fourth, and fifth costse are very prominent, 

 the second, as usual, being the most so. The first or anterior costa is rounded off; and 

 the third is faintly indicated, though distinct enough throughout the whole length of the 

 crown ; at the base there is a rather deep sulcus between the second and fourth costse. 

 The anterior vallum, " bourrelet," or " guard," which is well developed, is nearly 

 horizontal when the tooth is held in its natural position. It terminates at the inner 

 and anterior angle, and does not extend at all on the inner face of the anterior coUine. 

 The posterior vallum (" posterior collis," B. Dawk.) is deeply notched in the middle and 

 without a median cusp. It is prolonged into a strongly developed ridge, or " bourrelet," 

 which crosses the inner face of the posterior colline obliquely from above downwards, 

 nearly to the base of the crown, and terminates in the median sulcus in a very minute 

 cusp, as shown in fig. 2. 



The coULnes are slender and tapering. The anterior valley is wide, and traversed by 

 a strong crista (combing-platej, which arises from the angle of junction of the hinder 

 colline with the dorsal lamina. The uncus (" crochet ") is represented by a very thin 

 projecting plate, which appears, in the deeper part of the valley, to meet the crista so as 

 to circumscribe a small pit. The posterior valley is much expanded, and, owing to the 

 depth and width of the notch in the posterior vallum, very open. A small posterior 

 crista or " combing-plate " projects into this valley from the inner wall of the dorsal 

 lamina. 



The surface of the enamel, which is about 0"'06 thick where it is unworn, is marked 

 with very fine parallel sulci, and, in parts, with equally delicate transverse rugse. 



2. The tooth represented in figs, 4 and 5 appears to be the first right upper molar. 

 It is much more worn than the preceding ; and, in addition to this, the posterior vallum 

 is entirely broken away. It measures about 2'' in either direction ; and what remains 

 of the crown is about 2" in height. The second dorsal costa is very prominent, whilst 

 the others are represented only by low rounded elevations. The uncus (" crochet ") 

 comes ofi' at a right angle with the hinder colline, and curves slightly outwards, 

 reaching nearly across the anterior valley. In thickness and sculpture of the surface the 

 enamel of this tooth corresponds with that of the premolar above described. 



3. The tooth represented in figs. 6 and 7 appears to be the corresponding molar of the 

 opposite side. It is more imperfect than the last ; but from what remains of it its 

 character would seem to be identically the same. 



In both these teeth the posterior vallum is too much broken to afford any evidence 

 either for against the existence of a median cusp. 



4. The small molar represented in fig. 8 has lost nearly the whole of the dorsal 

 lamina. From the dimensions of the remaining portion, however, it may be concluded 



