396 FOSSILS FKOM PERIM ISLAND. 



holds in many of the osseous remains from the crag ; like the 

 latter, the Perim bones, under the action of the sea, wear 

 down into a polished vitreous surface. 



DllTOTHEEIUM. 



The first of these remains to be noticed is a fragment 

 (Plate VI. fig 3) consisting of the posterior half of one of the 

 inferior molars of a species of Dinotherium. The correspond- 

 ence of the specimen with the teeth of the large European 

 species is so complete in the form of the gable-shaped grind- 

 ing ridge, its transverse direction, and the reflected marginal 

 bidges into which it swells out on either side, together with 

 the characteristic crenulation of the edge, that there can be no 

 doubt of its belonging to the genus Dinotherium. The pecu- 

 liar ' talon ' or heel ridge is developed m the same degree and 

 with a like amount of crenulation along its edge. The frag- 

 ment is represented in section in Plate VI. fig. 3, the internal 

 structure exhibiting the same agreement with that of the 

 European Dinotherium (fig. 4) indicated by the external form. 

 The centre is occupied by a rhomboidal core of arenaceous 

 matrix marking the form of the unossified pulp nucleus. I 

 have compared it minutely with a corresponding section of 

 the same tooth (the penultimate of the lower jaw) of Dino- 

 therium giganteum (fig. 4) from Eppelsheim ; and the only 

 perceptible difference is, that the angle formed by the ridge 

 of the ivory is more acute, and the enamel thicker in the 

 Indian than in the European form. Perhaps no conclusion 

 can be safely drawn from this observed difference of angle in 

 the ivory ridge ; as it may be a peculiarity of the individual. 

 The greater thiclaiess of enamel is probably of more import- 

 ance, and may represent a mark of specific distinction. The 

 specimen, however, is much too defective to warrant any 

 opinion in regard to the relations of the Perim fossU to the 

 European species, except that it was quite as large as the D. 

 giganteum. We are fortunately able to determine the position 

 of the tooth in the jaw with some confidence. The upper 

 grinders in Dinotherium have a long low basal ridge in front 

 and behind; while the same teeth in the lower jaw have 

 hardly any ridge in front, and the hind one is consider- 

 ably more developed than in the upper grinders, so as to form 

 a strongly marked ' talon ' or heel. The Perim fossU ex- 

 hibits this heel of large size, while the presence of an impres- 

 sion on the posterior surface proves that there was a tooth 

 behind it. It, therefore, belonged to the penultimate molar 

 of the lower jaw, and apj^arently to the left side. 



In short, there can hardly be a doubt about the specinaen 

 belonging to a species of Dinotherium. The only question 



