760 B. W. KITNKEL 



44. The columella auris originates wholly external to the otic 

 capsule and is made up of stapes and extracolumella. The foot 

 plate occupies the fenestra vestibuU and rests upon the crista 

 substapediaUs; the stalk of the columella is slender and sUghtly 

 sinuous; the extracolumella is mushroom-shaped. 



45. A distinct processus interhyalis extends medially and ven- 

 trally from the ventral angle of the extracolumella. 



46. The ramus hyomandibularis nervi faciaUs extends pos- 

 teriorly dorsal to the columella and at the level of the latter gives 

 off the chorda tympani in a lateral direction. This nerve then 

 cm-ves anteriorly, crossing the columella dorsally, and bends 

 ventrally in front of the Eustachian tube. 



47. Meckel's cartilage is strongly developed. The two car- 

 tilages meet by a strong sjanphysis anteriorly. The processus 

 retroarticularis is poorly developed. 



48. The corpus hj^ale is pentagonal, with the apex directed 

 anteriorly. The short cornua hyalia are not segmented from 

 the corpus. The cornua branchiaha primum and secundum are 

 both large and segmented from the corpus. A separate epibran- 

 chiale primum is present. 



49. The processus linguaUs arises as a pair of anteriorly directed 

 rods from the anterior end of the corpus hyale, but at the stage 

 modelled the two have grown together. 



50. The cartilago entoglossaUs appears for the first time at 

 a later stage than that modelled. 



51. The squamosum is a thin plate of bone lying parallel to 

 the outer side of the quadratum. 



52. The quadrato-jugale is not laid down in the embryo till 

 a later stage than that at which most of the investing bones 

 are laid down. 



53. The zygomaticum, together with the postfrontale, com- 

 pletes the orbit of the eye posteriorly. 



54. The maxillare, as in the adult, exhibits a processus palati- 

 nus, a processus alveolaris, and a processus praefrontalis. Its 

 posterior end is perforated by a foramen for the passage from 

 above of the ramus maxillaris nervi trigemini which continues 

 forward lateral to the processus alveolaris. 



