From what has now been stated respecting the various circumstances which may tend to aggravate or alleviate the existing degree of pelvic deformity, it will be seen how incorrect and unpractical must be the attempt to classify the means of treatment merely according to the dimensions of the pelvis. To assert that within certain limits of pelvic contraction the child can be delivered by the natural powers, and that beyond these limits the forceps must be used; and that where it proceeds to a certain extent farther, it can only be delivered by perforation, &c. is evidently objectionable: for there are no two cases alike, even supposing that the degree of pelvic contraction is exactly similar; hence, on the one hand, we might (under such fallacious guidance) be induced to trust to the natural powers when they are wholly incompetent to the task, and on the other, to have recourse to art when the real condition of the case justified no such interference.[126] With regard to the diagnosis and treatment in the case of obliquely distorted pelvis (pelvis obliqué ovata,) our data are still too scanty to enable us to give any decided rules: the immobility of the head, although the antero-posterior diameter appears of its full length, the shortness of one oblique diameter, and consequent undue pressure upon the head in this direction, and the unusual length of the other, are the characteristics which we have observed in the only case of the kind which has come under our notice during life. In all the cases of labour rendered difficult by this condition of the pelvis, which have been collected by Professor Naegelé, the perforation has been strongly indicated; and where the forceps has been used, it has either failed, as with us, or if the delivery has been effected by this means, it has been attended with fatal consequences. In _exostosis_ of the pelvis we must be guided by our knowledge of the healthy pelvis, and by our carefully ascertaining the form and size of the bony growth, and in what degree it is likely to impede the passage of the child. As in cases of simple projection of the promontory, the head may be capable of passing, but in doing so becomes more or less distorted: thus Dr. Burns quotes a case from Dr. Campbell, where from exostosis within the pelvis, the left frontal bone was so greatly sunk in, as to make the eye protrude. Professor Otto, of Breslau, mentions a woman who had pelvic exostosis being the mother of four children, in each of whom a small portion of the cranium was depressed and not ossified.