376 RHINOCEROS. 



C. In Signor CesellPs Collections, from Torre di Quinto and Ponte 



Mammolo. 



In Signor Ceselli's collections from Torre di Quinto there is an ante- 

 penultimate true molar, right side, of Rhinoceros. It is in nearly the 

 same stage of wear as the penultimate in the Sapienza Museum (p. 374), 

 though of the opposite side, and is very much smaller in all the dimen- 

 sions, but the height of the crown proves it not to be a milk molar. 

 The crochet forms a very open angle, and a combing plate is emitted 

 from the middle of the outer ridge converging a little towards the point 

 of the crochet. There is also a short combing process emitted from the 

 anterior colline overlapping the tip of the crochet, and a little above 

 it. Further, deep down in the valley, are additional denticular com- 

 plications, forming a ring or a loop, one leg joined to the outer ridge, 

 one to the outer colline : very complex. 



The disc of the posterior colline is directed backwards, with torsion 

 of the apex. There is a small intercolumnar tubercle and a good deal 

 of cement. In all the characters the tooth agrees with the Montpellier 

 R. megarhinus, and in general plan it is very like the drawing of the 

 milk molar. 



Dimensions. — Extreme length of crown, outer side, 22 in. Extreme ditto, inner 

 side, near base, 1/5 in. Transverse diameter in front near base, 2 - l in. Transverse 

 ditto behind, at enamel edge below (very oblique), 2'1 in. Greatest height, outer 

 surface, 2'1 in. 



The specimen is encrusted below with volcanic gravel. It has no 

 fangs, and is rolled below. There is some cement at the mouth of the 

 transverse valley, and an abundant layer of it on the posterior valley 

 lining the surface. 



Signor Ceselli's collection (from Ponte Mammolo) also contains a very 

 perfectly preserved second premolar, upper jaw, right side, of Rhino- 

 ceros, slightly worn (i.e. a little less than the milk molar of Ponzi, PI. 

 XXXII. fig. 7), and in the best state to show its characters. The summit 

 of the crown shows distinctly three fossettes, i.e. one formed by the 

 anterior transverse valley, one by the posterior valley, and the third an 

 oval pit included between the termination of the crochet and the comb- 

 ing plate, emitted from the middle of the outer ridge nearly in front of 

 the dorsal vertical ridge. The two are fused into a confluent wall, of 

 which the combing plate is the thickest. The posterior valley has in- 

 truded into it, from the posterior outer vertical groove (which resembles 

 in form that of a horse), a very thick blunt plate dividing the end of the 

 valley into two branches. The termination of the anterior valley (exclu- 

 sive of the third fossette) is somewhat reniform, concavely parallel to the 

 posterior end, and free from any minor plates. The anterior disc forms 

 a narrow strip, little worn ; the posterior disc is nearly the same, and 

 has not much obliquity. There is no torsion, no posterior colline at 

 the apex, and no intercolumnar mammilla, but a well-marked basal bour- 

 relet to the inner side. The outer surface resembles the molar of a horse. 



Dimensions. — Length of crown, outside, T45 in. Length of ditto, inner side, at 

 basal bourrelet, l'lin. Length of ditto, in middle, to ditto, 1*35 in. Transverse 

 ditto, in front, base, l - 6in. Transverse ditto, behind, 1-6 in. Height of crown, 

 outside, l - 7 in. 



The specimen has volcanic sand matrix, and is rolled below ; the 

 fangs are entirely gone. There is no cement remaining. The enamel 

 is smooth. It is from Ponte Mammolo (Monte Sacro). 



