AND A DENTAL NOTATION. 
497 
senting the fourth of the typical dentition,” instead of c?4, and so on, the descrip- 
tions must have run to much greater length, and have levied such a tax upon the 
attention and memory as to have proportionally enfeebled the judgment and impaired 
the power of seizing and appreciating the results of the comparisons. 
Each year’s experience strengthens my conviction that the rapid and successful 
progress of anatomy depends greatly on the determination of the nature or homology 
of the parts observed, and on the concomitant acquisition of the power of denoting 
them by symbols equivalent to their single substantive names. 
In my work on the ‘ Archetype of the Vertebrate Skeleton,’ I have denoted most 
of the bones by simple numerals, which, if generally adopted, might take the place of 
names ; and all the propositions, e. g. relative to the centrum of the occipital ver- 
tebra, might be predicated as effectually and intelligibly of the figure 1 as of the word 
‘ basioccipital.’ The symbols of the teeth are fewer, are easily understood and re- 
membered, render unnecessary the endless repetition of the verbal definition of the 
parts, harmonize conflicting synonyms, serve as a universal language, and express the 
author’s meaning in the fewest and clearest terms. 
The Entomologist has long found the advantage of such signs as <?and ? , signify- 
ing male and female, and the like ; and it is time that the Anatomist should avail 
himself of this powerful instrument of thought, instruction and discovery, from which 
the Chemist, the Astronomer and the Geometrician have obtained such important 
results. 
Description of the Plates. 
PLATE XXXni. 
Fig. 1. Side view of the skull of a very young Phacochcerus JEliani, natural size, with 
the outer walls of the alveoli removed to expose the deciduous molars, pre- 
molars and true molars, in situ. 
Fig. 2. The grinding series, composed of milk-molars and true molars, from the 
upper jaw. 
Fig. 3. The same from the lower jaw. (The symbols are explained in the text.) 
PLATE XXXIV. 
Fig. 4. Grinding surface and side view of the crowns of the molar series of the upper 
jaw of a young Phacochoerus ^tiani. 
Fig. 5. Grinding surface and side view of the crowns of the molar series of the lower 
jaw of the same skull. 
3 s 
MDCCCL. 
