RHINOCEROS LEPTORIIINUS. 377 



In the same collection from Torre di Qninto there is also a penulti- 

 mate, or antepenultimate true molar upper jaw, left side, considerably 

 more advanced in wear than the others, and differing in some degree 

 from them in the general form of the crown (PI. XXXII. fig. 8). It 

 is more advanced in wear even than the detached R. hemitcechus tooth 

 brought for comparison, and the worn summit is much flatter than any 

 of the others, except Ceselli's very old compressed tooth. The general 

 contour of the crown is more square, and with less inequality between the 

 front and posterior diameters, approaching somewhat in this respect R. 

 hemitcechus. There are two valleys, the posterior of which is triangular 

 and ground low, and the inner slopes in a more shelving manner than in 

 R. hemitcechus. The middle valley opens into a triangular fissure ; it is 

 then bent nearly at right angles, by the intrusion of the crochet, and ter- 

 minates in a complex cul cle sac, which is three-lobed, or trefoil- shaped. 

 The termination of the middle valley is not unlike a more advanced degree 

 of the large penultimate in PL XXXII. fig. 4. A thick short plate is pro- 

 jected backwards from the anterior colline overlapping the direction of 

 the crochet, and pointing parallel to it from the opposite side ; the ordi- 

 nary combing plate from the outer ridge is projected inwards at right 

 angles to the apex of the crochet, but more as a deep-seated denticle, 

 the apex of which is still partly free. The crochet makes the third 

 division. The crochet differs very much in direction from the other 

 specimens. It is thrown forwards at a right angle, but with none of 

 the boot-shaped thickening of R. hemitcechus. The length of its inner 

 border is fully equal to the width of the posterior colline disc. There 

 is a small intercolunmar tubercle at the mouth of the valley. The an- 

 terior colline presents a sausage-shaped broad disc ; the posterior barrel 

 has somewhat of a horse-shoe pattern (from the posterior valley), but 

 the disc is very wide. The anterior outer vertical groove is wide and 

 deep ; but the outer edge of the crown is less angular in its outline 

 than usual, the points having been probably abraded by rolling. The 

 anterior overlapping sinus is much more pronounced than in R. 

 hemitcechus. 



The crown differs in its general pattern a good deal from the others. 

 The crochet is at right angles, but it is not the crochet of R. hemitwchus. 

 It certainly is not of R. tichorhinus. On the whole, I regard it as an 

 unusual form of R. megarhinus. The greater width at the inner side 

 and the abrasion of the outer edge give the peculiar appearance. 



Dimensions. — Length of crown (antero-post.), outside, 2-25 in. Length of ditto 

 in middle, 21 in. Length of ditto at inner side, about 1'95 in. 



The fangs are wanting and replaced by volcanic sand matrix. The 

 fangs had been rolled. The enamel is smooth and rather thin ; the ce- 

 ment is entirely gone. 



In the next place there is an antepenultimate (penult. ?) true molar, 

 upper jaw, right side, very far advanced in wear, of large proportional 

 size, but very much compressed (PI. XXXII. fig. 9). It retains the fangs, 

 perfect to their points. An oblique fracture (at a) has damaged a small 

 portion of the posterior barrel, and another recent (at b) has removed the 

 anterior outer angle and the layer of enamel. The surface of the ivory 

 here shows some very beautiful bluish black dendritic crystallization 

 penetrating into the ivory. The crown is oblong across (the dispropor- 

 tional width to length being much more than is shown in the figure), and 



