330 ROBERT J. TERRY 



the cavum nasi within, and are shaped externally somewhat 

 Hke a pair of spindles pressed together, making a single strong 

 framework, the cartilaginous ethmoidal skeleton, at the anterior 

 end of the skull. 



The length of the cartilaginous ethmoidal skeleton is equal to 

 about one-third that of the entire cranium. Its anterior half 

 projects free beyond the brain case; its posterior half, terminat- 

 ing on each side in the posterior cupola, is subcerebral in posi- 

 tion. Here it is continuous with parts in the orbito-temporal 

 region: the trabecular plate passing into the septum nasi and 

 roof of the posterior cupola, the commissura spheno-ethmoidalis 

 joining the lateral nasal wall. An extensive roof, tectum nasi, 

 is in the anterior half of the ethmoidal skeleton; an incomplete 

 one, lamina infracribrosa, in the posterior. The roof goes over on 

 either side into the paries nasi. The interior room of the nasal 

 skeleton opens into the cranial cavity by the fenestrae olfactoriae, 

 and upon the face through the fenestrae narinae. The floor of the 

 capsule, solum nasi, is very incomplete, presenting a great fenestra 

 basalis, within the compass of which are the paraseptal cartilages 

 standing next to the nasal septum. The side walls within, present 

 the beginnings of the complex of turbinals in the form of simple 

 inrollings and elevations. 



The tectum nasi (figs. 1, 3, 27 to 30) is furrowed in the mid- 

 line of its dorsal surface by the sulcus supraseptalis, deepest an- 

 teriorly, extending from the fenestra olfactoria to the level of the 

 fenestra narina. On either side the roof is highly arched and 

 passes laterally into the anterior region of the paries nasi. 



The side wall (figs. 3, 4) presents three regions: an anterior, 

 continuous with the tectum nasi, a middle region occupied by the 

 rounded prominentia lateralis, and a posterior area, the planum 

 antorbitale. Two grooves demarcate the prominentia lateralis 

 from the anterior and posterior regions. One of them, the sul- 

 cus laterahs anterior, at first pursues a curved course from the 

 olfactory window near the mid-line, cephalo-ventrad between 

 the tectum nasi and prominentia lateralis. This part of the sul- 

 cus stands opposite the crista semicircularis within the nasal 

 capsule and is interrupted by the epiphanial foramina of which 



