478 HOMOLOGY OF PALATINE PROCESS, 



investigation by Mr, R. H. Burne that the palatine process is 

 distinct from the premaxillary in an embryo Rabbit as large as 

 8 cm. Furthermore, Albrecht and Sutton have both maintained 

 that the palatine process is a distinct element from the pre- 

 maxillar}'- proper, though owing to their evidence being largely 

 pathological their views have not been generally accepted. Sutton 

 holds that the palatine process is the homologue of the " vomer " 

 of the fcJuhf/opsida, and that the mammalian vomer is represented 

 by the parasphenoid in the lower forms. Whether he is correct 

 or not in his Ichthyopsidian homologies I am not in a position to 

 definitely determine; but I think there is very strong evidence in 

 favour of the homology of the mammalian palatine process of the 

 premaxillary with the so-called " vomer " of at least the lizard 

 and snake, and in the present paper I shall bring forward a few 

 facts from Comparative Anatomy and Embryology in favour of 

 such a view. 



For some time I have been engaged in the study of the compara- 

 tive anatomy of Jacobson's Organ, and having studied the anterior 

 nasal region of a very large number of mammals and reptiles by 

 means of microscopic sections, I have come across a number of 

 interesting facts in connection with the ^^I'esent subject. 



In mammals the organs of Jacobson, as is well known, are 

 supported by the " recurrent cartilages" — developments of the 

 trabecular cornua, and as the cartilages are almost invariably 

 developed to a similar degree to the organs, the close connection 

 between the two is manifest. Furthermore, the cartilaginous 

 f ramew^ork of each organ rests on a bony support curved to fit the 

 cartilage, and Avhich is almost invariably anchylosed to the pre- 

 maxillary forming its palatine process. When the organ of 

 Jacobson is well developed and much elongated, its bony support 

 is correspondingly long, while when the organ is rudimentary the 

 palatine process is short or absent. So that not only is there a 

 close connection existing between the organ and the cartilage, but 

 also an intimate association l^etween the cartilage and the 

 supporting bone. 



