As to the use of the Latin terms and their equivalents in English form, we have made a practice of employing in the text sometimes one, sometimes the other; this has the advantage of giving variety, and of impressing the interchangeability of the Latin and English forms on the mind of the student. Where a given structure is called by two equally well-known 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 illustrate 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 applying 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 topographical 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, signifying always the same _direction_ without necessary reference to any given structure. For example, _cranial_ means not merely toward the _cranium_, 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 _craniad_ of the cranium itself. _Lateral_ signifies away from the middle plane; _medial_ toward it. _Inner_ and _outer_ or _internal_ and _external_ are used only with reference to the structure of separate organs, not with reference to the median plane of the body.