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Show 36 MR. W. H. FLOWER ON THE [Jan. 14, the other families of the group, or of speaking of them as specially "subursine." .. Ailurus (an unfortunate name for an animal so essentially Arctoid) appears to me to be an isolated form ; but until more is known of its anatomy, a very definite position cannot be assigned to it. Its dentition, though remarkably modified in character, is numerically that of the Procyonidce; but certain cranial peculiarities already pointed out, and its Asiatic habitat, lead me to concur with Mr. Turner in placing it in a distinct family. The Mustelidee constitute" a large, widely diffused, and somewhat disjointed group, but exceedingly difficult to reduce into natural subfamilies. The most aberrant or s'pecialized are the Otters, which, ending with Enhydris, run parallel to the Bears towards the Pinnipedia. °In order to exhibit at one glance the general result of this examination, I have arranged the various groups of the Carnivora in a diagrammatic plan (see p. 3/), which has obviously a great advantage over a linear series in showing cross relationships, especially as it attempts to indicate, by the distances the groups are placed apart, the amount of affinity between them*. A tree has long been a favourite image by which to illustrate genealogical descent ; and we are generally accustomed to have side-views of such trees presented to us, with the stem, main boughs, and smaller branches growing from them, all in perfect order. But tbe ancestral records of our existing fauna are so imperfect that it would be hopeless, from our scattered fragments of knowledge of them, to attempt at present to construct such a view of the descent of any zoological group. What we may, however, do with tolerable certainty is to take a careful survey of the top of the tree (to keep up the simile) as far as it has now grown, the only part that is completely exposed to our view, and make out the mode in which the component branches are now arranged. The diagram is intended to indicate the general outline of what may be called the Carnivora tree at its present stage of growth, seen from above; or it may be said to represent a transverse section of all the diverging genetic lines, showing the amount of differentiation of the groups, and the directions they have respectively taken at this particular epoch. Similar sections, taken at different geological periods, would probably present very different appearances. Groups now sharply separated might in other times have been united by intermediate forms ; and other highly specialized groups would be seen which have now entirely disappeared. The value of this plan all depends upon whether that great zoological problem, interpretation of true affinity, has been rightly solved. It is probable that a longer and more minute study of the details of the organization of different members of the order than has yet been given will introduce many modifications in this rough sketch ; it is not too presumptuous, however, to hope that ultimately it mav be so perfected that every genus and even species will have its appropriate place assigned to it. * Prof. Milne-Edwards in 1844 (Annales des Sciences Naturelles), and on several subsequent occasions, has made use of similar plans to illustrate his views of classification. |
