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in the British Museum, belongs to this species. Rhinoceros 
tichorliinus , is synonymous with the Rhinoceros antiquitatis of 
Blumenbach. 
R etkuscus (Falconer). — Rhinoceros etruscus differs from the 
above-mentioned Rhinoceros tichorliinus, in having an incomplete 
nasal septum. The animal had a comparatively slight and slender 
form when compared with R. tichorliinus. It possessed two horns. 
The enamel is much smoother and much thinner, than in the 
molars of R. tichorliinus. 
This species is abundant in the forest-bed, which is the only 
deposit in this county in which it has been fouud. It is also found 
in the Pliocene deposits of southern France and of the Val d’Arno 
in Italy. 
R. leptoriiinus (Cuvier). — This species is the original and typical 
Rhinoceros leptoriiinus of Cuvier, and is synonymous with the 
Rhinoceros megarhinus of Christol. It is the only Pliocene or 
Post-Pliocene species that had not a nasal septum. The form of 
the skull is very narrow as when compared with Rhinoceros 
etruscus ; it agrees with R. etruscus in the enamel of the teeth not 
being rugose or so thick as in R. tichorliinus. The remains of this 
animal have been found in the forest-bed, where, however, they are 
not so numerous as those of R. etruscus. 
Genus EQUUS. 
Equus plicidens (Owen). — If we compare the fossil molars of 
Equus with those of the recent species, we find the enamel ridges to 
be far more plaited in the former. The transverse diameter of the 
molar teeth is considerably less than in the recent species of simi- 
lar size. Equus plicidens in this respect resembles very much its 
ancestor Hi'pparion. The species is found in the old land sur- 
face under-lying the crag in the forest-bed, and dredged up off the 
Norfolk coast from post-glacial deposits. 
Genus HIPPOPOTAMUS. 
Subgenus TETRAPROTODON. 
II. major (Owen). — The genus Hippopotamus comprises two sub- 
genera, llexaprotodon and Tetraprotodon ; so named on account of 
the number of the incisor teeth being in the former case six, and in 
the latter four, above and below. 
