548 MAMxMALIAN AND REPTILIAN VOMERINE BONES, 



lizards, I arrived at the conclusion that the process is morpho- 

 logically an anterior vomer even when not formed from a distinct 

 centre, and is the homologue of the dumbbell bone of Orniiho- 

 rhynchus and of the so-called "vomer" in at least lizards and 

 snakes. For this element I proposed the name of pre vomer as 

 more in harmony with the general terminology than "anterior 

 vomer." 



In 1896 Symington (8), who had some years previously described 

 the dumbbell bone of Ornithorhynchus, replied to Wilson, and 

 showed that the dumbbell bone in most of its relations agrees 

 with the palatine process of the premaxillary with which he 

 regards it as homologous. He is not inclined to regard the 

 palatine process as vomerine, since it is only exceptionally formed 

 from a distinct centre. 



This year Wilson (9) has published a most interesting paper on 

 the anatomy of the snout of the young Ornithorhynchus and 

 Echidna, of which a preliminary notice was issued two years ago. 

 In this paper he confirms the observation of Newton Parker that 

 the dumbbell bone is developed as two splints to Jacobson's 

 cartilages, and further shows that in the early young the pre- 

 maxillaries not only meet in the middle line but send back 

 palatine processes. These processes are quite distinct from the 

 dumbbell bone ending some distance in front of its developing 

 splints. 



Van Bemmelen (10) also last year published an important paper 

 on the Monotreme skull in which he supports the pre vomerine 

 theory of the dumbbell bone. I regret, however, that I have not 

 yet seen the paper. 



The Development of the Mammalian Premaxillary. 



The large majority of anatomists have always regarded the 

 premaxillary bone with its palatine process as a single element, 

 and I think it may be regarded as an undoubted fact that in the 

 large majority of mammals the palatine process is developed along 

 with the premaxillary, and that only in comparatively few forms 



