392 THE NASAL REGION IN EUTAENIA. 



plates, one to proceed down the outer surface of the Organ of Jacob- 

 son, the other, to proceed in opposite direction, on the outer wall of 

 the passage and terminate in the middle of its height. The lower 

 plate is found in other sections to enter the pedicle (Fig. 2, pel,) of 

 the Organ of Jacobson, and partly fuses there with the basal portion 

 of the vomer. In the section represented it does not so enter, its 

 place being occupied by the cartilage which passes out from the 

 pedicle and lines the outer under face of both plates of the septo- 

 maxillary, and ultimately in sections behind this reaches the turbinal 

 ingrowth, with the cartilage of which it unites. (Figs. 2, 3, 4, tb.) 

 The upper half of the pedicle is tilled with cartilage throughout, 

 (tb' 2, 3.) The turbinal cartilage extends over the nasal cavity to- 

 connect in front with the wing of the nasal septum, which terminates- 

 interiorly with a rounded edge between the cupped crests of the 

 vomer of each side. (Figs. 2, 3, 4, Sept.), 



In a section through the anterior termination of the maxillae, the- 

 latter with the premaxilla form a horizontal plate with a plate of 

 cartilage, also horizontal, in its centre. In a section behind this 

 the cartilage is concave on its upper face, and the osseous 

 piece above it, is the ascending process of the premaxilla. Below,, 

 are two basal pieces, not distinctly separated from each other, or 

 from the maxillae now somewhat laterally. Behind this again the 

 cartilage takes a U form, the wings of which give off on each side a 

 nearly vertical transverse plate, forming a prenasal wall, and reach- 

 ing the cheek in front of the anterior nasal opening. Between the 

 wings of the main cartilage, now the nasal septum, the ascending 

 process of the premaxilla extends and forms a vertical plate. (Fig. 

 6, pra. ) Immediately behind the transverse prenasal wall of each 

 side, the septom axillary commences rod-like, and separated from the 

 similarly shaped vomer by a thin sheet of cartilage continuous with 

 the transverse prenasal wall. The basal portions of the premaxilla 

 (prb) do not extend much further behind this point. The septo- 

 maxillary becomes flattened as it proceeds backward, its transverse 

 axis directed outward and downward, and applied in this manner to 

 the wall of the nasal cavity. It is still separated by the cartilage, 

 above described, from the vomer. When the Organ of Jacobson is 

 reached, the septomaxillary has acquired considerable thickness and 

 forms its anterior wall, while the cartilage enters the pedicle, in the 

 anterior half of which the two mentioned bones fuse, althoiigh incom- 



