BY J. T. WILSON. 131 



observations we propose first of all briefly to review, as it is 

 chiefly to these authors that we owe our knowledge of the detailed 

 anatomy of the bone. Symington's chief results were obtained by 

 the study of series of coronal sections. 



After referring to its shape, Turner (loc. cit.) states that the 

 dumb-bell bone " consists of two symmetrical and lateral halves 

 united mesially by a suture, the line of which may be seen on the 

 palatal surface of the bone, though the two halves obviously 

 become fused at a comparatively early period of life." He also 

 states that it is situated "in the hinder part of a fibrous meni- 

 bi-ane, which is attached behind to the anterior free border of the 

 palate plate of each superior maxilla, on each side to the inner 

 border of the intermaxilla, &c.," and that " the edge of the dumb- 

 bell bone is surrounded by the membrane." He further states 

 that "the upper surface of the dumb-bell bone lies immediately 

 subjacent to the anterior somewhat expanded end of the vomer, 

 which is fused with it along its mesial line." He then proceeds 

 to refer to its relation to the uaso-palatine or incisive foramina, 

 which open on each side of and close to the isthmus or intermediate 

 portion of the dumb-bell bone as seen from the palate, and he 

 concludes that in its relation to the incisive foramina, the dumb- 

 bell bone corresponds with " that portion of the intermaxillary in 

 other Mammalia which lies between the incisive foramen and the 

 mesial palatal suture "; and that " the more anterior part of the 

 roof of the mouth does not undergo an ossific change, but remains 

 as fibrous membrane, except in the limited area where the dumb- 

 bell-shaped bone is produced." He then goes on to examine the 

 argument for the theory that the dumb-bell bone is the homologue 

 of the prenasal bone of the pig, as this was expressed by Flower, 

 following Owen's later view, and he sums up in favour of its 

 correspondence to the mesial element of the premaxilla rather 

 than to the prenasal, as follows : — The dumb-bell-shaped bone " is 

 inferior to the vomer and fused with its inferior Vjorder ; it has no 

 relation to the anterior nares ; it enters into the constitution of 

 the hard palate, and it forms the inner boundary of the entrance 

 into the naso-palatine canal. In its position and relations it 



