346

ESSAY ON CLASSIFICATION.

will be an additional reason with us for communicatingoccasional extracts from it to the reader. Mr. M’Leay’stheory will be best understood by consulting his diagram;for he has not, as we have already remarked, defined anyof the vertebrated groups. Condensing, however, theresult of his remarks, we shall state them as resolvableinto the following propositions: 1, that the natural seriesof animals is continuous, forming, as it were, a circle, sothat upon commencing at any one given point, and thencetracing all the modifications of structure, we shall be im-perceptibly led, after passing through numerous forms,again to the point from which we started > 2, that nogroups are natural which do not exhibit such a circularseries; 3, that the primary divisions of every large groupare ten, five of which are composed of comparatively largecircles, and five of smaller,—these latter being termedosculant, and being intermediate between the former,which they serve to connect; 4, that there is a tendency,in such groups as are placed at the opposite points of acircle of affinity, ‘ to meet each other’; 5, that one of thefive larger groups into which every natural circle is divided,‘bears a resemblance to all the rest,—or, more strictlyspeaking, consists of types which represent those of eachof the four other groups, together with a type peculiar toitself.’ These are the chief and leading principles whichMr. M’Leay considers as belonging to the natural system.We shall now copy his diagram, or table of the animalkingdom, and then endeavour, with this help, to explainthe system more in detail.”