332 ROBERT J. TERRY 



tinues caudally into the dorsal surface of the trabeqjilar plate 

 and laterally goes into the planum antorbitale. A slight median 

 ridge, crista interorbitaUs, separates two shallow fossae lodging 

 the olfactory tracts. 



Ventrally, the nasal capsule presents the great fenestra basalis 

 (figs. 1,2), the relations of which to the cavum nasi are somewhat 

 complicated. It is limited laterally by the ventral margin of 

 the planum antorbitale and by the maxillo-turbinal. In the 

 region of the latter it is very narrow from side to side, and is 

 partly covered ventrally by the paraseptal cartilage hanging 

 down from the septum. Anteriorly the basal window reaches to 

 the lamina transversalis anterior which stands between it and 

 the fenestra narina. The caudal limit is formed by the lamina 

 transversalis posterior. Further relations of the basal window 

 will be better understood when considered in connection with 

 the description of the nasal cavity. 



The solum nasi is represented by the two transverse laminae 

 and the horizontal portion of the paraseptal cartilage (figs. 2, 3, 

 13, 25, 26). The lamina transversalis posterior (figs. 2, 13, 25) 

 forms the floor of the posterior cupola and appears in the sec- 

 tions and in the model as an inrolling of the caudo-ventral part 

 of the planum antorbitale. Its medial margin is turned dorsad; 

 in its caudal half it is applied closely to, but not actually joined 

 with, the keeled trabecular plate behind the level of the vomer; 

 in its cephalic half it is free, being separated from the nasal sep- 

 tum by a narrow stretch of the fenestra basalis. Here the lam- 

 ina is overlapped by the caudal end of the vomer. The band- 

 like lamina transversalis anterior (figs. 2. 3, 13), incompletely 

 chondrified, bounds the fenestra narina ventro-laterally, connect- 

 ing the septum nasi with the paries nasi. It is continuous with 

 both parts, that is to say, a zona annularis is present. Its hori- 

 zontal, broader, septal end stands opposite the anterior half of 

 the OS incisivum. Followed laterally, the lamina undergoes a 

 curve in the dorsal direction, and comes to lie in a sagittal plane. ^ 



' In cat embryos of about 70 mm. the lamina transversalis anterior presents 

 two backwardly directed processes which embrace the funnel-shaped depression 

 of the floor leading into the incisive duct. These have been called by Zucker- 



