work received whilst writing out these pages, in which, for instance, Begoniaceæ, Melastomaceæ, Gesneriaceæ, Burmanniaceæ, and Orchideæ, are collected into one series, whilst Memecyleæ, Bignoniaceæ, and Iri- deæ, are far removed from them.
It appears to me, therefore, that whilst in an artificial or analytical system for finding out the name of a plant, one prominent character is selected to mark out each division; in a natural or synthetical system, on the contrary, for the arrangement and study of plants, the affinities according to which they are grouped should be judged of by the combination of as many and as constant characters as possible, derived from all parts of the plants; but that, in both cases, characters must be assigned. "Character non facit genus," it is true; but a genus without a character is of no assistance to the mind of the naturalist.
[Read before the Royal Physical Society of Edinburgh, Nov., 1860.]
In works on human anatomy it has been customary to compare the articular surfaces of the atlas, and the superior articular surfaces of the axis, with those of the oblique processes of other vertebræ, as if they were homologous, notwithstanding the apparently anomalous manner in which, according to that view, the first and second spinal nerves must be considered as emerging from the spinal canal. The circumstances which have led to this comparison being made, are merely the rapid diminution in size of the intervertebral discs from the thoracic region up to the axis, and a general similarity of appearance between the articular surfaces of the atlas and axis and those of succeeding vertebræ: and though the impropriety of this comparison has been exposed in very explicit terms by Prof. Henle,[1] there is still room for a few remarks as to the precise parts of other vertebrae to which the surfaces in question correspond.
In order to arrive at a just conclusion upon this subject, we shall find it advantageous to examine the atlas in the bird. In it we find on the posterior aspect a pair of true oblique processes passing backwards, to articulate above the intervertebral foramina with a corresponding pair of processes of the axis, similar to those of succeeding vertebræ; while inferiorly there is a cartilaginous surface which forms, with the body of the axis and its odontoid process, a joint similar to those between the succeeding bodies of vertebræ. On the anterior aspect of the
- ↑ Henle, Handbuch der Syst. Anat. des Menschen, I., p. 42.
