RHINOCEROS ETRUSCUS. 365 



The penultimate premolar is equally perfect on botli sides, and in 

 the same stage of wear. They both show the basal bourrelet round 

 the inner barrels, but not very pronounced. 



P.m. 4, or the last premolar, has the anterior outer angle of the crown 

 broken on the right side ; it is beautifully perfect on the left, which 

 shows the crown but very slightly advanced in wear ; the discs of both 

 barrels are confluent with the outer disc. The posterior valley is well 

 denned and intact behind ; the anterior transverse valley has intruded 

 into it a large crochet process, and two large accessory plates (or 

 combing processes), proceeding parallel to each other from the outer 

 ridge, and converging towards the crochet. A distinct ring of enamel 

 isolating a pit is situated on the base of the crochet, the whole causing 

 a complex pattern to the convolutions of the transverse valley. Fine 

 parallel and wavy grooved lines of enamel are beautifully shown on 

 the inner surface of the enamel. This tooth, like the others, shows a 

 distinct basal cingulum ; it is more triangular in form than the two 

 which precede it. 



T.m. 1, the first true molar, is quite perfect on the right side ; on the 

 left side the posterior barrel is broken on its inner surface. The crown 

 is more advanced in wear than any of the others, but still not very 

 much so, being not yet half worn. The posterior valley is quite intact 

 behind, but is narrower and more vertical than in the premolars. The 

 transverse valley is divided into two nearly distinct portions by a very 

 thick crochet, protruded i'rom the posterior barrel ; the outer division 

 has no accessory plates intruded into the fissure from the outer longitu- 

 dinal ridge ; the inner division forms a narrow triangular fissure. The 

 crochet is emitted at a very open angle from the posterior barrel, more 

 open even than in R. leptorhinus, and totally different from that seen 

 in li. hemitaechus. There is a little basal mammilla between the barrels 

 at the inside, but not a trace of an anterior basal bourrelet to the 

 anterior barrel. The teeth are very much alike on both sides. The 

 central termination of the middle valley does not exhibit the duck's 

 head pattern, figured by Gervais and De Christol in the teeth of It. 

 megarliinus. There is a little tendency to the peculiar twist of the 

 posterior barrel near the apex of the crown ; the anterior outer vertical 

 groove is broad, but shallow ; the angle boldly overlaps the last pre- 

 molar. 



T.m. 2, or the pemdtimate, on the right side, is nearly perfect, but the 

 outer anterior angle is broken off vertically on the left side. The tooth 

 in general form resembles very much the antepenultimate just des- 

 cribed, but is less advanced in wear ; the crochet is also, as in it, emitted 

 at an open angle. The transverse valley is divided in two by the 

 crochet, the inner division being triangular, without any accessory 

 plates or complication whatever. The summit of the posterior barrel 

 has the peculiar compressed contortion well marked. The crochet 

 advances nearly into contact with the anterior barrel; the discs form 

 narrow bands of wear, which are confluent throughout. There is not 

 a trace of a basal cingulum on either side. 



T.m. 3, or the last true molar, is broken partly on both sides, but in 

 different directions, so that what is wanting in the one is supplied by 

 the other. The crown is but very slightly affected by wear on the right 

 side. It is of a distinct triangular ibrin, all the parts converging to a 



