346 ESSAY ON CLASSIFICATION. 



will be an additional reason with us for communicating 

 occasional extracts from it to the reader. Mr. M'Leay's 

 theory will be best understood by consulting his diagram ; 

 for he has not, as we have already remarked, defined any 

 of the vertebrated groups. Condensing, however, the 

 result of his remarks, we shall state them as resolvable 

 into the following propositions: 1, that the natural series 

 of animals is continuous, forming, as it were, a circle, so 

 that upon commencing at any one given point, and thence 

 tracing 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 no 

 groups arc natural which do not exhibit such a circular 

 series ; 3, that the primary divisions of every large group 

 are ten, five of which are composed of comparatively large 

 circles, and five of smaller, these latter being termed 

 osculant, 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 a 

 circle of affinity, 'to meet each other'; 5, that one of the 

 five larger groups into which every natural circle is divided, 

 'bears a resemblance to all the rest, or, more strictly 

 speaking, consists of types which represent those of each 

 of the four other groups, together with a type peculiar to 

 itself.' These are the chief and leading principles which 

 Mr. M'Leay considers as belonging to the natural system. 

 We shall now copy his diagram, or table of the animal 

 kingdom, and then endeavour, with this help, to explain 

 the system more in detail." 



