222 Professor Clark on a Case 



face, the eye-ball presents two cornese of different sizes: in the 

 less perfect, one large transparent disc. Plate 11. 



In the less perfect face, below the junction of the eye-brows 

 is a very small fleshy tubercle, which is the only rudiment of 

 a nose. In the other face this tubercle is considerably larger : 

 is evidently bony from its resistance : is covered by a loose flap 

 of skin : and, when this is turned down over the eye, the tubercle 

 is found to present a cell on either side, separated by a middle 

 septum. Plate 12. Fig. E and F. 



The mouth in the more perfect face is fairly formed. When 

 the lips are separated, a well developed tongue is seen. The 

 mouth of the less perfect is much smaller. No tongue is here 

 visible : but this, as will be afterwards found, is only an apparent 

 defect. This mouth opens by an aperture behind, about a line 

 in diameter, into another cavity : into which cavity the mouth of 

 the more perfect face also opens. 



With respect to the osseous system, I shall detail only what is 

 peculiar and unusual : the bones of the spinal column, of the 

 pelvis and limbs of each foetus, and the ribs, being normal. 



The bones of the head, standing upon each vertebral column, 

 unite to form a single cavity for the common brains of the two 

 foetuses. 



On the top of either column is placed an occipital bone to 

 which the temporals and parietals are attached in the usual way. 

 The parietal bones, corresponding to one column, meet those cor- 

 responding to the other column, at their anterior and superior 

 angles which are truncated ; membrane alone uniting the truncated 

 angles, and thus forming on the vertex of the common head a 

 large fontanelle. Between the truncated and the anterior inferior 

 angles of the corresponding opposite parietal bones, are situated the 



