1846.] OWEN ON A TOOTH OF DICHOBUNE CERVINUM. 421 



exactly the proportions which might be expected in the upper mo- 

 lars of that species ; having the same superior transverse diameter, 

 as compared with the antero-posterior diameter, which the upper 

 molars of all herbivorous and most other mammals present, com- 

 pared with the lower ones. (Compare figs. 1 and 3 with 5 and 6.) 



The Anoplotherian character of the tooth is shown by the large 

 size of the lobe p, fig. 1, and the subgeneric peculiarity by the con- 

 tinuation of its dentinal base with that of the inner and anterior 

 lobe id, at the early stage of attrition presented by the crown of the 

 tooth in question. In the large and typical Anoplotheria the lobe 

 preserves its insular form and uninterrupted contour of enamel until 

 the crown is more worn down. In this respect, as in the modifica- 

 tions of the lower molar teeth, the genus Dichobune shows its closer 

 affinity to the true Ruminants ; but the little fold of enamel dividing 

 the lobe id from p distinguishes the upper molar tooth in question 

 from that of any Ruminant. From the genus Moschus (fig. 3) it 

 further and more particularly differs in the equal concavity of the 

 outer surface of the outer lobes o, o, the anterior of which in Mos- 

 chus is traversed by a strong vertical ridge (fig. 3, o). The basal 

 ridge (r) along the inner side of the crown of the upper molar of 

 Dichobune distinguishes it from those oi Moschus and of any known 

 Ruminant of corresponding size. For the better elucidation of 

 these distinctive characters, figures of the homologous teeth of Mos- 

 chus moschiferus (figs. 3, 4 & 6) are subjoined. 



4. On the Wealden Beds of Brora, Sutherlandshire, with Remarhs 

 on the Relations of the Wealden Strata and Stonesjield Slate 

 to the rest of the Jurassic System, and on the marine contem- 

 porary of the Wealden Series above the Portland Stone. By 

 Alexander Robertson, Esq., F.G.S. 



[The publication of this paper is postponed for the present.] 



