XIIL] THE FROG. 171 



two slender cartilages, the rhinal processes. Each of these 

 inclines towards the middle line and ends against the middle 

 of the posterior face of the ascending process of the pre- 

 maxilla by a vertically elongated extremity. An oval nodule 

 of cartilage is attached to the posterior face of the dorsal 

 end of the ascending process of the premaxilla, and serves 

 to connect it with the rhinal process. On the dorsal face of 

 the chondro-cranium, just above the point of attachment of 

 the rhinal processes, the external nasal apertures are situated, 

 and the outer and posterior margins of each of these aper- 

 tures are surrounded and supported by a curious curved 

 process of the cartilaginous ala the alinasal process. Where 

 the sphenoidal and the ethmoidal portions of the spheneth- 

 moid meet, a stout, transverse, partly osseous and partly 

 cartilaginous bar is given ofif, which is perforated at its origin 

 by the canal for the orbito-nasal nerve. It then narrows, 

 but becoming flattened from above downwards, rapidly 

 widens again, and its axe-head-like extremity abuts against 

 the inner face of the maxilla. The anterior angle of the 

 axe-head is free; the posterior angle is continued back into 

 a slender cartilaginous pterygoid rod which bifurcates poste- 

 riorly. The outer division passes into the. ventral crus of 

 the suspensorium. The inner division is the pedicle of the 

 suspensorium; it articulates by a joint with the anterior face 

 of the broad lateral process of the hinder part of the chon- 

 dro-cranium, which contains the auditory labyrinth and is 

 termed the periotic capsule. The Suspensorium is a rod of 

 cartilage, which lies between the squamosal and the ptery- 

 goid bones and, at its distal end, articulates with Meckel's 

 cartilage which forms the core of the ramus of the mandible. 

 At its dorsal end it divides into two divergent processes or 

 crura, of which the ventral crus has already been said to be 

 continuous with the pterygoid. The dorsal crus, on the 



