Of all animals the higher Vertebrata are the most complex; and among these the carnivores and hoofed animals (Ungulata) are highly differentiated.

And so definitely and precisely marked is the structure of each animal, that, in the present state of our knowledge, there is not the least evidence to prove that a form, in the slightest degree transitional between any of the two groups Vertebrata, Annulosa, Mollusca, and Coelenterata, either exists, or has existed, during that period of the earth's history which is recorded by the geologist.

This is a living population equivalent to that of a new continent in mere number; equivalent to that of a new hemisphere, if we take into account the small population of insects as yet found fossil, and the large proportion and peculiar organisation of many of the Vertebrata.

Turning to the Vertebrata, the only palaeozoic Elasmobranch Fish of which we have any complete knowledge is the Devonian and Carboniferous Pleuracanthus, which differs no more from existing Sharks than these do from one another.

Among the Vertebrata, however, there are a few examples which appear to be far less open to objection.

It is, in fact, true of several groups of Vertebrata which have lived through a considerable range of time, that the endoskeleton (more particularly the spinal column) of the older genera presents a less ossified, and, so far, less differentiated, condition than that of the younger genera.

To a certain extent, indeed, it may be said that imperfect ossification of the vertebral column is an embryonic character; but, on the other hand, it would be extremely incorrect to suppose that the vertebral columns of the older Vertebrata are in any sense embryonic in their whole structure.

So far, indeed, as the Invertebrata and the lower Vertebrata are concerned, the facts and the conclusions which are to be drawn from them appear to me to remain what they were.

But when we turn to the higher Vertebrata, the results of recent investigations, however we may sift and criticise them, seem to me to leave a clear balance in favour of the doctrine of the evolution of living forms one from another.

I propose to attempt to deal with this problem, so far as it is exemplified by the distribution of the terrestrial Vertebrata, and I shall endeavour to show you that it is capable of solution in a sense entirely favourable to the doctrine of evolution.

The case is different with the members of each great class, as the Vertebrata or Articulata; for here we have in the laws of homology, embryology, etc., some distinct evidence that all have descended from a single primordial parent."]

(Indeed!)"The usual classification of animals, is that of Vertebrata, Articulata, Mollusca, and Radiata.

" (Why?)"We are told by these naturalists that man belongs to the class called 'Vertebrata.'

He perceived Huxley's Vertebrata upon the side-table.

"From ovum to ovum is the goal of the higher vertebrata," the lecturer had said in his melancholy tones, and so had neatly rounded off the sketch of comparative anatomy he had been developing.

Then, before he could enter, the shabby person pushed past him and asked in a loud, vulgar tone: "Does Edna Pumpelly live here?" James stiffened in the approved style of erect vertebrata.

... VERTEBRATA.