324 • CHARLES CLIFFORD MACKLIN 



sphenoid, medially, and to the zygomatic arch (as yet incomplete) 

 laterally, a condition which does not obtain in the mature skull. 



Dorsal to the prominent frontal process of the superior maxilla 

 the isolated nodule of cartilage, known as the cartilago parana- 

 salis, is to be seen, lying lateral to the cavity for the' lacrimal 

 duct and below the small streak of membrane bone, which is the 

 anlage of the future lacrimal. Another smaller nodule of car- 

 tilage is seen near the back of the orbit lying against the upper 

 surface of the ectethmoid and may be known as the cartilago 

 paraethmoidalis. Separating the orbital from the nasal cavity 

 is to be seen the shell-like ectethmoid, bearing upon its cranio- 

 ventral aspect the small nasal bone. At the front of the nasal 

 cartilages appear the open anterior nares, separated by the 

 ventral border of the septum. 



Regarded from below (fig. 2) the model shows in the foreground 

 the mandibular (not shown in fig. 2) and upper part of the hyoid 

 arches. Behind these we see the semi-cylindrical ventral sur- 

 face of the planum basale, separated from the elongated, flat- 

 tened, ovoid partes cochleares by deep furrows. It is to be ob- 

 served that the anterior extremities of the latter do not project 

 beyond the planum. The forked structure at the root of the 

 planum, perforated for the hypoglossal nerve, is seen to be the 

 anterior commencement of the flattened, ring-like sides of the 

 foramen magnum, a downwardly projecting angle marking the 

 position of the future occipital condyle. Lateral to and above 

 the condyle there appears a stout cartilaginous process, which 

 supports the lower and anterior part of the otic capsule. This is 

 known as the processus paracondyloideus (Voit), and above it 

 is seen a wide opening, the jugular foramen (fig. 4). 



The two Meckelian cartilages (fig. 3) enclose an angle, rather 

 sharp ventrally, in which are found the structures of the floor 

 of the mouth. The inwardly curved palatine bones, with the 

 assistance of the inner laminae of the pterygoid processes (fig. 2), 

 imperfectly cut off the posterior part of the nasal cavity, and be- 

 tween the pterygoid laminae and the planum basale is seen the 

 space occupied by the naso-pharynx (fig. 10) . Attached to these 

 medial laminae, and indeed developed from their caudal tips, are 



