No man who spends any considerable portion of his time in the study of practical anatomy, i. e., actual dissections, can fail to note how great is the number of anatomic variations he meets. So common are these variations that it can not be exactly said which is typical normal anatomy, and which are the anatomic variations. In plain words, anatomy is not a study to be classed among exact sciences. I do not mean by this that there is not such a regular basis of anatomic science that safe anatomic rules can not be made, but the more closely we study the subject the more variations as to details we are compelled to record. To be sure, given the mandible of an animal, a femur, or even a tarsal bone, the nature of associated bones, their size, positions and forms can be deduced, and by further study even an