526 
ORIGINAL ARTICLES. 
the British Museum, and the Museums of the Boyal College of Sur¬ 
geons, of the Geological Survey, of Taunton, and especially of Oxford. 
In mapping out the teeth, I have adopted Brandt’s^ nomenclature 
as far as possible, and all the more readily, as it coincides with a 
system of terms that I had used for some time before his monograph 
came into my hands. 
§ 2. System oe Measurements. — The value of a system of 
measurements in accurately showing the relation of the parts 
measured to the whole tooth will be seen in its application in the 
following pages. As the crown varies in the relative size of its parts 
according to the state of wear, all the measurements are taken along 
the base, instead of the summit of the tooth. The four used below 
are numbered for the sake of reference, and will be referred to by the 
numbers at the beginning of each. All are taken in inches and 
tenths. 
1. Antero-posterior measurement, taken along the outside of 
crown. 
2. Antero-transverse measurement, taken across the anterior 
lobe of the tooth, from the middle of the anterior collis f 
to the middle of the anterior area, or at the neck of the 
anterior pair of fangs. 
8. Postero-transverse measurement, taken across the posterior 
lobe of tooth, or at the neck of the posterior pair of fangs. 
4. Circumference of base of crown. 
§ 3. Characteristics oe Permanent and Deciduous Molar 
Dentition. —The Molar series of the upper and lower jaw are far 
more closely allied to each other than at first sight appears. Com¬ 
posed of the same elements, modified for a special purpose in each 
tooth, they possess a large number of common characteristics. The 
crowns are traversed by two depressions of variable depth, with their 
entrances either open, or more or less closed. Of these, the anterior, 
always opening upon the inner side, is the Anterior Yalley [ A of 
fig. 1—7]J ; the posterior opening on the inner side of the lower, and 
the inner and posterior angle of the upper molars, is the Posterior 
Yalley [ B of figures].§ In front of the Anterior Yalley is the 
Anterior Collis || [ D ], while between the two valleys, the 
Median Collis^ [E ] forms the posterior wall of the one, the 
anterior of the other. The Posterior Collis ## [ P ], forms the 
* Brandt, £ De Bhinocerotis Antiquitatis seu Tichorini seu Pallasii structural 
etc. Trans, de St. Petersburgh, Yol. vii. pt. 2. (4to. 1849.) 
f Vide § 3. 
J ‘ Vallis Anterior,’ Brandt. ‘ Vallon Oblique’ in the Upper Molars.—Cuvier. 
§ ‘ Vallis Posterior,’Brandt. In the Upper Molars ‘ Echranchrure au bord Pos- 
terieur,’ Cuvier. ‘ Fossette Posterieure,’ Blainville. 
|] ‘Collis Anterior,’ Brandt. In the Upper Molars ‘ Colline Seconde,’ Cuvier. 
^ ‘ Collis Medius,’ Branc^t. In the Upper Molars, ‘ La Troisieme Colline,’ 
Cuvier. Christal. 
** ‘ Collis Posterior,’ Brandt. In the Upper Molars, ‘ Bord Posterieur de la Dent,’ 
Cuvier. Blainville. 
