SKULL OF A HUMAN FETUS OF 40 MM. 409 



border of the ectethmoid, the incisura post-transversalis (figs. 

 3 and 12), behind the processus paraseptalis, the latter being the 

 representative of the anterior transverse lamina of the rabbit 

 (Voit). The ventral surface of the Sakterwulst slopes downward, 

 forward and inward to the upper part of the incisura narina. 

 Upon the edge of this there js, at this point, a small projection, 

 the representative of the cartilage cupularis of the lower forms 

 (fig. 12). 



The ventro-caudal portion of the paries nasi is raised into a 

 slight eminence, and upon the ventral edge of this, which bounds 

 the incisura narina, the processus alaris superior appears (figs. 

 2 and 12) this being, however, but rudimentary in man when 

 compared with such fonns as the rabbit. The most prominent 

 feature of the lower edge is the elongated and slender paraseptal 

 process, which points inward, backward and downward. 



The solum nasi is formed mainly by the inferior nasal concha, 

 which appears as the inturned lower edge of the paries nasi, and 

 in part by the rudiments of the laminae transversales anterior 

 and posterior, represented respectively by the processus para- 

 septalis and the processus cupularis posterior. The dorsal 

 portion of the inferior concha is corrugated, and presents a free 

 posterior edge, which meets its median border at a right angle. 

 This dorsal edge is inwardly continuous with the lower extremity 

 of the middle concha (fig. 12), where it joins the inner aspect 

 of the planum antorbitale; with the latter it forms a notch, 

 lodging the ventral portion of the upper border of the palate 

 bone, and known as the ventral palatine notch (figs. 2 and 12). 

 A rounded ridge, directed backward and inward, appears upon 

 the lower surface, and separates two grooves, the medial being 

 the more well-marked. This ridge is represented in the floor 

 of the middle meatus by a wide groove which runs backward 

 and inward to terminate by passing over the dorsal edge of the 

 inferior concha, which thus shows a marked concavity upward. 



The ventral portion of the solum is narrow and more sloping 

 than the dorsal, and is also smoother. It terminates ventrally 

 at the post-transverse incisure. The medial border of the 

 inferior concha is thickened except at its extremities, and forms 

 the lateral boundary of the basal fissure (fig. 12). 



