Few will, we believe, in the present day be disposed entirely to deny that, _ceteris paribus_, the external formation of the skull, or rather the shape of the brain as shown by the formation of the skull, is a general index of the mental power of the individual to whom it belongs. Look over a collection of busts, or portraits, of eminent men, and, with scarcely an exception, they will be found to have high and capacious foreheads; while uncivilized races, and born idiots, are lamentably deficient in this respect. The difficulties of phrenology exist in its details, which by many have been carried out into degrees of subdivision certainly not warranted either by the anatomical structure of the brain, or by any empirical data as to the form of different crania, and the biography of the individuals to whom they have belonged. Where, in the existing state of our knowledge, the proper mean may be, it is perhaps difficult to say; but it would have been well, we think, had Dr Prichard given us a little more explicitly his opinions as to what extent phrenology (we use the word in its broadest sense) may be fairly relied on. As far as we can gather from the scattered passages in his book, he seems to take a rational view of it; but a little less caution would certainly have been more instructive to his readers, not only on the subject of phrenology, but on many of the connexions between physical structure and the habits to which such structure is adapted. This is a _hiatus_ in Dr Prichard's work, the filling up of which would add much interesting matter, and serve to weave together acts which at present are disjointed and isolated; giving the book a dry character, and preventing its arresting the attention of the reader. Throughout a larger portion of the work also, we have, in every third page or so, a minute description of the complexion, hair, &c., of different people; which, however valuable as matter of record, becomes tiresome and uninteresting as a continuous narrative, and would be much better thrown into a tabular form, as matter of reference only, if incapable of being so linked as to present a plausible theory. The following passage is the most explicit we can find on the subject of the connexion between the _physique_ and _morale_, and, at the same time, will serve to introduce the three varieties of skull which the author deems principally worth notice:-- "If any method of subdividing the human family into groups, is likely to be of any particular advantage in elucidating the natural history of the species, it must be one founded on some relation between the physical characteristics of different tribes and the leading circumstances of their external condition.