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 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 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 



