404 CHARLES CLIFFORD MACKLIN 



der. The cranial border, almost parallel with the caudal border 

 of the mesethmoid, presents near the ventral process a long, 

 slender limb 1 cm. in length, which curves upward and forward, 

 to come into close contact with the dorsal tip of the ventro- 

 lateral process, and thus to reach the most ventral extremity of 

 this cartilaginous mass. On the left side this off-shoot, which 

 may be known as the cranio-ventral process (figs. 2 and 18), is 

 disconnected from the septum, though only separated therefrom 

 by a thin sheet of perichondrium, but on the right side a con- 

 nection to the septum appears near the ventral end of the proc- 

 ess. This connection, however, is very meager, the surround- 

 ing perichondrium almost cutting it off, and it would seem to be 

 secondary. The cartilage of which the plate is composed is 

 similar to that of the septum within. The two plates enclose a 

 space, open below, which is filled with dense connective tissue, 

 and at the dorsal border of the cartilages the ventral tips of the 

 vomer are seen in it. The ventral process is connected laterally 

 with the lateral Jacobsonian cartilage by cells of procartilage. 



The lateral member of the anterior paraseptal cartilages (figs. 

 2-3) is a short, curved rod, 1 cm. in length, whose concavity 

 is directed downward, forward and slightly inward, lying almost 

 parallel with the cranio-ventral process of the medial mass which 

 is to be found immediately internal to it. The entire lateral mass 

 is of a younger type of cartilage than that composing the larger 

 Jacobsonian cartilage, and upon examining the sections it is 

 seen that it is connected with the latter at •a point near the ventral 

 process by procartilage. Otherwise the lateral mass is quite 

 free. The adjacent portion of the lateral wall is marked by the 

 prominent paraseptal process (fig. 2), whose tip is composed of 

 young cartilage, and between this and the lateral Jacobsonian 

 cartilage there is a zone of loose tissue which suggests an earlier 

 connection between these points such as exists in the rabbit 

 (Voit) in the form of the anterior transverse lamina. The ect- 

 ethmoid would then be united with the medial Jacobsonian 

 cartilage, the lateral member being probably a rudiment of this 

 lamina. 



