^^ 



F jc. 



FIG. 200. SECTIONS OF THE NOSE or VARIOUS VERTEBRATES. 



A D, Illustrating the various ontogenetic and phylogenetic stages of the Jacobson's organ of 

 Urodeles ; in A its position is median, and in D lateral. E, Gymnophiona, in which the 

 organ becomes separated from the main nasal cavity. F, Lacerta agilis. G, Ornithorhynchus 

 (After Symington.) H, Placental Mammal ; I, the same, in longitudinal vertical section. 



a, epiderm ; c.j, Jacobson's cartilage ; d.n, naso-lacrymal duct ; g.m, intermaxillary gland : </.., 

 nasal gland ; jc, Jacobson's organ ; mx, maxilla ; na, main nasal cavity ; n.o, olfactory 

 , trigeminal nerve; o.d, dumb-bell shaped bone (prevomer) ; sp, septum nasi. 



nerve 



