Another form of mole is where the uterus is filled with a large mass of vesicles of irregular size and shape like hydatids, which appear to be the absorbing extremities of the veins of the chorion distended with a serous fluid; it is difficult to distinguish these from real hydatids; the more so, as Bremser asserts that he has occasionally met with real hydatids among them. Perhaps the mode of their attachment will in some degree assist the diagnosis: these vessicles, or _hydatids of the placenta_, as they have been called, are attached over a large portion of the uterus,--an arrangement we believe, not generally seen in real hydatids, which are mostly attached to a single stalk or pedicle. Indeed, it may be doubted if the masses of vesicles which are occasionally expelled from the uterus are ever true acephalocysts, as they are invariably connected with a blighted ovum, and are, therefore, formed as before observed, by a dropsical state of the venous radicles of the chorion. A variety of other molar growths have also been enumerated by authors; in fact, "the term _mole_ has been rather vaguely applied to almost every shapeless mass which issued from the uterus, whether this proved to be coagulated blood, detached tumours, or a blighted conception." (Churchill, _on the Principal Diseases of Females_, p. 153.) Thus a fibrinous cast of the uterus, which has been formed by a coagulum of blood, from which the colouring matter has been drained, has been called a fibrous mole: these, however, may easily be distinguished from real moles, which are invariably the product of conception: from inattention also to this circumstance, fungoid, bony, and calcareous tumours have been described as so many species of moles.[49]