26 HAY. [Vol. IV. 



far forward as the section passing through the lens, at which 

 point the frontals and the vomero-palatines begin to enter into 

 the side walls of the brain-cavity. Contrary to Dr. Wiedersheim's 

 statement concerning the orbitosphenoidal bone in the adult, it 

 is in my specimen higher in front than behind. 



Following the trabecular walls forward, we find that before 

 the ossifications have disappeared the cartilage has divided 

 itself into two bars, an upper and a lower, corresponding to those 

 of the larva, which are designated by Na.C and 7>. in Figs. 

 3 and 4. The lower bar is the continuation of the trabecula. 

 Opposite the eye, the upper bar is a very slender rod, which 

 does not lie nearly so far to the outside of the middle line as it 

 does in the embryo, a circumstance due probably to the narrow- 

 ing of the snout. As soon as the nasal-sac is reached, this rod 

 expands outward, while its inner edge lies against the descend- 

 ing process of the frontal bone. Just where the olfactory nerve 

 pierces the frontal, the cartilage again divides into an inner and 

 an outer portion. The inner division runs forward in the angle 

 between the facial and the descending processes of the frontal 

 and coalesces with the X of the cartilaginous nasal septum. 

 The outer division extends forward over the upper outer side 

 of the nasal-sac until opposite the bony internasal septum, where 

 its outer edge unites with the cartilage that underlies the nasal- 

 sac ; its inner edge meanwhile extending inward meets and 

 unites with the advancing border of the cartilage that covered 

 the inner and upper wall of the nasal-sac. In other words, we 

 may say that the nasal-sac is roofed over with a cartilage that 

 has in it a large fontanelle, and that this roof mesially coalesces 

 with the cartilaginous nasal septum, while externally it coalesces 

 with the band of cartilage which expands beneath the nasal-sac. 



Where the internasal septum is formed by the premaxilla, 

 the cartilage is missing on the inner side of the nasal-sac, but 

 above, below, and on the outer side, the cartilage is unbroken. 

 When the alveolar process of the premaxilla is reached, no 

 cartilage is found immediately over it ; but on the outside of 

 the sac and above it, the cartilage continues to the borders of 

 the external nostrils, while just before the nostril is reached, the 

 cartilage is expanded so as almost to surround the passage. 



On its lower inner side the nasal cartilage sends a prong into 

 the angle between the body and the alveolar process of the 



