MB. W. B, DAWKINS ON RHINOCEROS MEGARHINUS. 403 



Brandt with a few modifications, as in my first essay on the denti- 

 tion of JR. tichorhinus. 



The detailed description of the teeth is based upon an examina- 

 tion of between 70 and 80 specimens. 



So far as I can make out the synonomy of R. megarhinus and 

 from figures and descriptions, it appears to be the equivalent of 

 B. Schleiermacheri* of Kaup, B. KircJiherqensisf of Jager, and R. 

 incisivus (in part) of Cuvier.J M. deBlainville confounds it with the 

 leptorhine of Cmier, and the equivocal species from the A"al d'Arno.§ 



The teeth of Rhinoceros megarhinus have been obtained from 

 three localities in the valley of the Thames, in which alone its re- 

 mains occur in Britain. All the figured specimens were found at 

 Grays Thurrock, and are preserved in the British Museum. In the 

 cabinets of Dr. Spurrell and Mr. Grantham are some upper molars, 

 from the south bank of the Thames, near Crayford, in Kent, while 

 in the beautiful collection of Mammalia, from Ilford, made by Dr. 

 Cotton, E.G.S., are two molar teeth. All the three species — the 

 megarhine, leptorhine, and tichorhine, are found together at Cray- 

 ford and Ilford. 



The three species are bicorn. 



§ 2. Enamel STRrcTURE. — The sculpturing on the enamel surface 

 aff"ords a ready means of determining the teeth of the three species. 

 In the tichorhine the enamel is traversed by irregular rugae, with 

 but the faintest trace of parallelism, in the megarhine by fine striae, 

 for the most part parallel, that scarcely roughen the smooth surface, 

 while in the leptorhine it partakes of the characters of both species, 

 being smoother and more regularly marked than the former, less so 

 than the latter. In the milk dentition, and especially in the lower 

 molar series, these characters are not so well marked. 



§ 3. Milk Dentition oe R. megarhinus. — Analogy w^ould lead us 

 to expect to find but little difference in the milk teeth of the three 



* Isis, 1832, p. 898-904. 



f Ueber die Fossilen Sangethiere welche in Wiirtemberg aufgefunden worden 

 sind Von Prof. Jager, Stuttgardt, 1835, folio, p. 179. 



X M. de Sen-es Bibliotlieque Universelle, 183.5, in his " observations sur les Rhi- 

 noceros Fossiles et Humatiles," and De Christol, in his paper quoted above, prove 

 that of Cuvier's three species, tichorhine, leptorhine, and incisor-bearing Rhinoce- 

 roses, the first is the only valid one. The other portion of Cu^der's R. incisivus, Kaup 

 relegates to the large hornless rhinoceros of Darmstadt, Acerotherium incisicum. 

 1832, p. 34, tab. xviii.) 



§ Ostcographie Art. Rhinoceros, PL xiii. 



2 e 2 



