56 THE SKELETON OF THE CAT. 



large jugular foramen (//), for the ninth, tenth, and eleventh 

 nerves. Opening into the mediocaudal margin of the jugular 

 foramen is the smaller hypoglossal foramen, for the twelfth 

 nerve. 



The craniomedial end of the tympanic bulla projects craniad 

 as the styliform process (/). Just laterad of this process is the 

 opening (/) into the tympanic bulla by which the tuba auditiva 

 or Eustachian tube passes into the middle ear. A faint groove 

 for the tube passes craniomediad from this opening, on the sur- 

 face of the sphenoid. Craniolaterad of the opening for the tuba 

 auditiva is the foramen ovale (); craniad of this the foramen 

 rotundum (/) is faintly indicated. On the surface of the 

 sphenoid just craniad of the styliform process of the bulla tym- 

 pani is the minute opening of the pterygoid canal (t). The 

 orbital fissure and optic foramen are not seen in the ventral 

 view. 



The middle region of the ventral surface is narrow: it is 

 formed by a trough-like fossa which is bounded laterally by the 

 pterygoid processes (nt) of the sphenoid and the perpendicular 

 plates of the palatines (). Ventrad of this lies, in the natural 

 condition, the soft palate, converting the fossa into the nasal 

 portion of the pharynx or nasopharynx. Craniad this fossa is 

 bounded by the free caudal edges of the palatines; beneath 

 which the fossa communicates with the nasal cavity by the two 

 choanae (p). Laterad of this median fossa are visible in the 

 ventral view parts of the temporal and orbital fossae, bounded 

 laterally by the zygomatic arches (/). 



The cranial part of the ventral surface is a somewhat tri- 

 angular plane area formed by the palatal portions of the pala- 

 tines (s), maxillari.;s(9), and premaxillaries (10), which together 

 constitute the hard palate (palatum durum). Laterad and 

 craniad this area is bounded by the alveolar borders of the 

 maxillaries and premaxillaries bearing the teeth. The hard 

 palate is marked near the cranial border of the palatine bones 

 with two or more foramina which form the cranial termination 

 of the posterior palatine canal (q). Two faint grooves pass 

 from these foramina a short distance craniad, gradually con- 

 verging: these are known as the palatine grooves (r) (sulci 



