BY R. I3R00M. 201 



tary opening, it is found to form a very broad plate by having 

 become united to the alisphenoid cartilage. The alisphenoid 

 -cartilage differs from that of the earlier stage in there being now 

 seen an upward growth from near the middle of the outer side. 

 This ascending process lies between the second and third branches 

 ^f nerve v., and the Gasserian ganglion itself rests, as in the 

 earlier stage, on the alisphenoid cartilage. The carotid foramen 

 •ds still of large size, and is completely surrounded by cartilage. 



The auditory capsule is large and fairly well choudrified. The 

 slower part is oval, and the chondrification is less perfect. This 

 part lodges the small cochlea, as yet uncoiled, and the greater 

 -part of the saccule and utricle. The upper part of the capsule 

 -in well choudrified, and is structurally continuous with the orbito- 

 sphenoid bar. It protects the upper part of the utricle and the 

 -semicircular canals. The fenestra ovalis is situated a little below 

 the middle of the capsule. From the upper part of the capsule 

 there is given off a cartilaginous ridge which passes downwards 

 and protects the tympanum. This is the tegmen tympani. It is 

 not quite clear whether it is a part of the auditory capsule or a 

 ^process from the exoccipital. 



Behind the lower part of the capsule there is an elongated 

 fenestra for the passage of nerves ix., x., and xi. The 

 occipital cartilage behind this is broad and well developed. 

 There are two foramina, both apparently for nerve xii. There 

 "is no apparent differentiation between the basioccipital and the 

 exoccipital, but the supraoccipital can be demarcated from the 

 exoccipital. 



Meckel's cartilage is well chondrified, and is continuous with 

 the anterior process of the maljeus. The malleus is fairly large, 

 but the capitulum is not very marked, and the manubrium 

 rather short and directed markedly inwards. The incus articu- 

 lates with the malleus in the usual manner, and is of the usual 

 miammalian shape. The stapes is large and is perforated. 



The hyoid articulates in part with the processus longus of the 

 incus, and in part with the margin of the tegmen tympani. 



