THE NASAL REGION IN EUTAENIA. 393 



pletely. The septomaxillary undergoes another change in form at 

 the hinder half of the Organ of Jacobson it gradually loses the pro- 

 longation on the outer and under surface of the Organ, which is there 

 replaced by the vomer. It also rises and becomes more closely applied 

 to the nasal wall. On the other hand, the cupped crest of the vomer 

 becomes prolonged outward under the septomaxillary and parallel 

 with it. This portion of the vomer is much fenestrated to allow a 

 passage to the Organ of Jacobson for the olfactory nerve bundles. 

 Below, the basal portion reaches outward, and finally unites with the 

 superior prolongation on the outer surface of the Organ. 



The vomer thus surrounds and envelopes the posterior, as the septo- 

 maxillary does the anterior, termination of the Organ of Jacobson 

 behind which it divides into two portions, the inferior quickly dis- 

 appearing, the superior losing its horizontal process rises, and with 

 its' fellow of the opposite side forms a capsule for the lower half of 

 the nasal septum, now oval in section. Approaching the choana of 

 its side, it descends again to apply itself to its inner wall, and 

 terminates by sending a plate outward over the choanal roof to unite 

 with the palatine bone. 



As before stated, the wings of the nasal septum pass out over the 

 nasal cavities down their sides to connect with the turbina] carti- 

 lages. The latter are provided in their front half with a concavity 

 on the outer face of each, to which the Nasal Gland of Midler accom- 

 modates itself. This concavity deepens as the cartilage is followed 

 backward, the edges approximating and forming ultimately behind a 

 closed tube, containing a separate portion of the gland. (Fig. 4, Mg'\. 

 This tube ends blindly with the turbinal ingrowth. 



In front a plate of cartilage, continuous with the turbinal, passes 

 around the nasal opening, and is connected with the transverse pre- 

 nasal wall. (Figs. 6, 7, nc, nc.) Below, the turbinal is connected 

 with the cartilage of the pedicle of the Organ of Jacobson by a 

 narrow transverse plate passing under the septomaxillary. This 

 transversely directed plate of cartilage is continued backward into 

 two pieces, which in a transverse section containing the opening of 

 the Organ of Jacobson are arranged, one immediately under the 

 outer half of the latter, the other some distance laterally. (Figs. 3, 

 4, lc' , lc".) These are the lachrymal cartilages, and are described 

 below in connection with the lachrymal duct. 

 28 



