"In none of the cases, the particulars of which have come to my knowledge, has there been any trace of rachitis; nor have any of the symptoms, appearances, and morbid changes been observed which characterize mollities ossium coming on after puberty. None of these cases have been traced to the effects of external violence, as falls, blows, &c.; nor has there been any complaint of pain in the region of the pelvis, inferior extremities, &c." (_Das Schräg Verengte Becken_, p. 12.) "With respect to the strength, colour, structure, &c. of the bones of this species of deformed pelvis, no difference could be observed between them and the bones of young and perfectly healthy subjects; not a trace either in form or other respects could be detected of those changes which usually result from rachitis or mollities ossium; and but for this distortion and some other slight irregularities, which required close inspection to detect, these pelves would have been looked upon as well-shaped, and of sufficient capacity." (Naegelé, _op. cit._ p. 11.) In some specimens no trace of anchylosis at the sacro-iliac symphysis has been observed; but whether this was the case throughout the union of the two bones we cannot say. Professor Naegelé is inclined to look upon them as modifications of the _pelvis obliqué ovata_, and certainly in the majority of known cases anchylosis has been found present. It is scarcely necessary to do more than enumerate other varieties in the form of the pelvis, which are occasionally met with: it is sometimes round, the transverse and antero-posterior diameters being of the same length; in other cases it possesses many of the characters which distinguish the male pelvis, being more or less triangular, deep, and with a contracted angular pubic arch. _Exostosis._ Lastly, the pelvis may be perfectly well formed, but the passage through it more or less interrupted by the exostosis: this is, perhaps, the rarest species of dystocia pelvica. It may arise from wounds of the periosteum, from fracture of the bones, callus, &c. and may vary in size from a small protuberance to a large mass, which completely fills up the pelvis.