36 ILLINOIS BIOLOGICAL MONOGRAPHS [36 



to the upper margin of the nasal organs, completely separating them in 

 this region from each other. The dorsal part of the verticale extends 

 backward a short distance over the planum basale; while anteriorly it 

 extends forward over the internasal space where it divides into three parts, 

 a short median rostrum continuous with the verticale, and a pair of alary 

 processes which extend ventrally and laterally, terminating near the tips 

 of the trabeculae. In a later stage these alary processes develop ante- 

 riorly and laterally to form the vault of the capsule. 



Anterior to the preorbital band, a wide band of cartilage, the lamina 

 externa, forms the side wall of the capsule. It is pierced by two foramina, 

 the smaller more posterior one for a small branch of the fifth nerve, while 

 the profundus passes through the larger, more anterior one. Winslow 

 (1898), in his early stage, describes a small antorbital process which 

 extends outwards and forwards from the anterior margin of the preorbital 

 band, much as in the Urodeles. In this stage, the anterior part of this 

 process has united to the lateral parts of the capsule, enclosing the foramen 

 above described, which must be the orbito-nasalis of Urodeles; so that it 

 would seem that the lamina externa is formed of elements of an ethmoidal 

 column and an antorbital process, although complete evidence as to the 

 former is lacking. 



Anterior to the foramen orbito-nasalis, the lamina externa widens 

 slightly, its dorsal margin extending more medially, reaches to the level 

 of the upper surface of the verticale, where a short process extends for- 

 ward, separated from the remaining externa by a deep notch through 

 which the superficialis passes to the nasal organ. Ventral to this notch 

 and in the same horizontal line with the foramen orbito-nasalis, is another 

 foramen through which a branch of the profundus nerve passes from the 

 capsule. 



Beyond this latter foramen, the lamina externa, more narrow than 

 before, extends forward a short distance, ending in a blunt process in line 

 with the anterior margin of the planum basale; while ventral to the foramen 

 it is united to the cornu trabeculae, which supports the anterior end of the 

 nasal sac, forming the only floor of the capsule, and enclosing the large 

 ventral choanal gap. 



I Winslow has described a small cartilage bar, lying near the trabecula, 

 ust beneath the preorbital band, which is unassociated with any other 

 part of the capsule. This he calls a palatine cartilage. In my material, 

 this small bar is directly in line with the anterior part of the pterygoid 

 process from which it is but slightly removed; and it would seem as though 

 it was a part of the pterygoid which may have chondrified independently, 

 or have separated from the more basal part of this process. Peter (p. 582, 

 1898) in his description of the pterygoid of Ichthyophis says: "Dagen 

 findet sich in seiner Verlangerung parallel der unteren Trabekelspange ein 



