PREFACE. vii 
names, we have used both, holding that the student should 
become familiar with each and recognize their identity of 
meaning. 
In general we have maintained the principle that the 
primary purpose of such a work as the present is not to illus- 
trate or defend any particular system of nomenclature, but to 
aid in obtaining a knowledge of the structures themselves. 
With this end in view, we have used such terms as would in 
our judgment best subserve this purpose, making the BNA 
system, as the one most likely to prevail, our basis. In apply- 
ing the system we have had to keep in mind a number of 
sometimes conflicting principles. In some cases the judgment 
of other anatomists will doubtless differ from our own; but this 
we feel to be inevitable. The matter of an absolutely uniform 
nomenclature is not ripe for settlement at the present time. 
Some further explanation is needed in regard to the topo- 
graphical terms, or terms of direction, used in the present 
work. We have adopted the BNA terms in this matter also. 
The terms superior, inferior, anterior, and posterior have been 
avoided, as these terms do not convey the same meaning in 
the case of the cat as they do in man, owing to the difference 
in the posture of the body. In place of these terms are used 
dorsal and ventral, cranial and caudal. As terms of direction 
these, of course, must have an absolutely fixed meaning, sig- 
nifying always the same d@vection without necessary reference 
to any given structure. For example, cvanzal means not 
merely toward the cranzum, but refers to the direction which is 
indicated by movement along a line from the middle of the 
body, toward the cranium; after the head or cranium is 
reached, the term still continues in force for structures even 
beyond the cranium. Thus the tip of the nose is’ considered 
to be crantad of the cranium itself. Lateral signifies away 
from the middle plane; medzal toward it. Juner and outer or 
internal and external are used only with reference to the struc- 
ture of separate organs, not with reference to the median plane 
of the body. 
In describing the limbs the convexity of the joint (the elbow 
or knee) is considered as dorsal, the concavity being therefore 
