KHINOCEROS LEPTOKHINUS. 395 



natural position, including the six molars of each side from the ante- 

 penultimate premolar (p.m. 2) to the last true molar (m. 3), inclusive. 

 (See Plate XXXI. fig. 1.) 



The molars (see Plate XXXI. fig. 1), on the whole, are admirably 

 preserved, better even than the Bologna specimen of R. Etruscus (PL 

 XXIX.), and in a beautiful state, so far as age goes, to show the dental 

 characters, t.m. 2 being about half way worn above the basal bourrelet, 

 and t.m. 3 with its apex only partially worn ; p.m. 4 and t.m. 1 of 

 either side much worn. 



The following are the principal dimensions on right side : — 



Extreme length of line of six molars from hind tubercle, last molar, to antepe- 

 nultimate p.m. 10-6 in. Length of three true molars outside, 6 - 2 in. Ditto in 

 middle, 5 - 8 in. Ditto of three premolars, 4-9 in. Length of p.m. 2, top, outside, 

 1-55 in. Width of ditto, greatest, 1'6 in. Length of p.m. 3, 1-8 in. Width of 

 ditto greatest (below bourrelet), 22 in. Length of p.m. 4 ditto, 1-9 in. Width of 

 ditto (greatest in front), below ditto, 2 - 3 in. Length of t.m. 1 (greater on left 

 side, but restored), about 2- in. Width of ditto in front (bourrelet worn away), 2'45 

 in. Length of t.m. 2, which is very perfect, 2 3 in. Width of ditto in front, 

 below bourrelet, 25 in. Length of t.m. 3 diagonally from anterior angle to basal 

 tubercle, 2-3 in. Width of ditto at base of front barrel, 2-25 in. 



General Remarks. — 1. The first point that strikes is, that the three 

 premolars have a very large basal cingulum, quite as large as that 

 figured by Christol. It is largest in the third and fourth, and very 

 oblique in its direction, rising gradually from the base of the anterior 

 barrel to the top, behind, of the posterior barrel {i.e. from the anterior 

 talon to the edge of the hind valley). 



2. The true molars have also a very distinct basal cingulum (!). This 

 is nearly worn away in the antepenultimate, but is shown in very bold 

 relief upon the anterior barrel of the penultimate, and interruptedly, but 

 quite clearly, on the posterior barrel. The same cingulum is shown 

 very boldly on the anterior barrel of the last true molar, but is not 

 exhibited on the posterior barrel of this tooth, which is narrow at the 

 base. 



3. In lieu of the rudimentary pit on the hind part of the base of the 

 last true molar, which is seen in the R. Etruscus of the Bologna Mu- 

 seum, the Imola tooth (t.m. 3) shows a distinct triangular or sagitti- 

 form lobe or tubercle (like a Celtic arrow-head), adpressed to the pos- 

 terior barrel, but separated from it at the apex by a very pronounced 

 notch. This tubercle is somewhat crenated at the apex, but utterly 

 distinct in form from that of R. Etruscus or R. hemitcechus. There is 

 not a trace of a posterior valley running up upon the posterior angle of 

 the last molar. 



4. The vertical external furrow of the anterior angle is broad and 

 very boldly defined by a deep groove in all the true molars, and also in 

 p.m. 4. This is shown also in p.ni. 3, but less boldly. In this respect 

 the teeth are very different from those of R. Etruscus. The other 

 ridges and furrows of the outer surface are also shown more distinctly 

 in the Imola specimen than in R. Etruscus. 



5. There is not the least indication of a basal bourrelet outside (as in 

 Aceratherium). 



6. The crochet in t.m. 2 makes an obvious angle with a re-entering 

 nick in its offset from the posterior ban-el ; the angle is much more 



