PEIMORDIAL CRANIUM OF THE CAT 319 



tion from before backward and laterally, on account of which 

 the ala temporalis stands in front, as well as to the side of the 

 processus alaris. Between the latter and the anterior pole of the 

 cochlear capsule extends a cartilaginous bridge, the commissura 

 aUcochlearis, forming the lateral boundary of the carotid fora- 

 men. It is quite distinct from the temporal wing, the two being 

 separated by the continuation of the zone of mesenchyma just 

 described. The processus alaris and commissura aUcochlearis 

 are, however, continuous, and together form an arch around the 

 front and side of the carotid foramen. 



The lamina ascendens (figs. 1, 2, 3, 23) of the ala temporahs 

 is a cartilaginous plate which extends laterally and dorsally to- 

 ward the commissura orbito-parietahs, but remains widely sepa- 

 rated from it. It is somewhat triangular in form, presenting 

 free margins, anterior and posterior, which meet laterally in a 

 rounded free point, and a base directed toward the obUque line 

 of junction with the alar process and alicochlear commissure. 

 The dorsal surface slopes from an intermediate longitudinal 

 ridge, forwaj-d and backward, thus presenting two subdivisions: 

 an anterior face entering into the floor of the spheno-orbital fis- 

 sure ; and a posterior, supporting the cephaUc end of the semilunar 

 ganglion and forming the floor of the epipteric cave. The longi- 

 tudinal ridge itself lies opposite the lower margin of the ala or- 

 bitahs and enters into the ventral boundary of the spheno-orbital 

 fissure. The ventral surface of the lamina ascendens overhangs 

 the mandible and gives origin to part of the pterygoid muscle. 

 A short canal, the forerunner of the foramen rotundum, traverses 

 the lamina ascendens from behind forward, giving passage to- 

 the maxillary nerve. The posterior margin of the ala is free and 

 limits anteriorly a broad, deep fissure whose posterior boundary 

 is the cochlear capsule. The fissure ends medially at the ali- 

 cochlear conmiissure and, like the spheno-orbital fissure, is open 

 laterally. To this gap, which has long been known, the name 

 fissura aUcochlearis may be given. Through it pass the mandib- 

 ular and the great superficial petrosal nerves, the former through 

 the incisura ovalis in the posterior margin of the lamina ascen- 

 dens, the latter traversing another notch, incisura lacera, and 



