332 KIIINOCEROS. 



blotches. A portion of the diastemal and incisive prolongation, which 

 is wanting in the Lyons skull, is fortunately present in the Milan 

 specimen. The series of molars is present on both sides, but the 

 summits of most of the crowns are more or less involved or concealed 

 by matrix, which has been left very nearly as when found by Cortesi. 

 Tbe following teeth are present or indicated : — ■ 



A. Right Side. — 1. Immediately behind the commencement of the 

 diasteme, on the right side, the empty socket is distinctly marked of a 

 single-fanged premolar, being the normal pre-antepenultimate (p.m. 1). 

 The alveolus is oval in the transverse direction, and about eight lines 

 in diameter. I have picked some of the matrix out of it, so as clearly 

 to define the pit, and am quite certain of the accuracy of the observa- 

 tion. The corresponding socket of the same tooth is present on the 

 left side, but has not been picked out to the same extent. 



2. The antepenultimate premolar or {p.m. 2). — The shell of the 

 crown of this tooth has been broken off, but it is fortunately preserved 

 on the left side, and will be noticed in the sequel. 



3. The penultimate premolar or (p.?n. 3) — The shell of enamel 

 nearly all round the circumference of this tooth is preserved, but the 

 central convolutions and the anterior inner barrel have been ground 

 down and destroyed by a recent crush. The salient point of the outer 

 shell of enamel is very high, and it almost looks at the posterior point 

 as if it had not been subjected to wear ; but this is very doubtful, 

 there being no ivory attached to determine the point. The correspond- 

 ing tooth of the opposite side is present nearly entire ; but the outer 

 half of the crown is covered by matrix which conceals the convolutions. 



4. The last premolar [p.m. 4) is present, and beautifully perfect. It 

 had evidently come but very lately into place, as the edges only of the 

 anterior and posterior barrels are slightly worn into narrow crescentic 

 discs, and the outer edge is also but slightly affected by wear. The 

 level of the crown is depressed below the level of both the tooth which 

 precedes it, and of that which is behind it ; it is in a considerably less 

 advanced state of wear than the next succeeding teeth (i.e. t.m. 1 and 

 t.m. 2), and therefore had come into place more recently than either 

 of them. The basal bourrelet is distinctly marked at the anterior and 

 posterior ends, but only very obscurely around the base of the inner 

 side, as a slightly crenulated inequality. The anterior and posterior 

 barrel ridges are nearly transverse and parallel, the posterior fossette is 

 very large and intact behind. The crochet plates are very complex, 

 forming four pectinate lamina?, which are directed forwards so as to 

 meet an accessory plate thrown off inwards from the outer ridge, which 

 divides the central termination of the middle valley into two nearly 

 equal divisions. In this respect, the tooth resembles very closely fig. 25 

 of De Christol's plate (see PI. XVIII. fig. 1), but with this difference, 

 that the crochet plates in the latter are only two, while in the Milan 

 tooth they are closely approximated and are tour in number. But De 

 Christol's tooth is more advanced in wear, and the crochet plates would 

 be reduced in number in the Milan tooth by further abrasion. One of 

 these plates advances so as nearly to meet the accessory outer combing 

 plate, and thus isolate a distinct fossette. There is a contortion of the 

 apex of the posterior barrel (as in PI. XVIII. fig. 1). 



On the opposite side the corresponding tooth is apparently wanting, 

 its place being occupied by matrix. This would indicate either that 



