38 PLEISTOCENE MAMMALIA. 



that with the basioccipital, which in the old animal is obliterated as completely as the 

 frontal suture of human anatomy. The sides are covered to a great extent by the overlap 

 of the anterior portion of the tympanic bulla, and in front by the guttural process of the 

 alisphenoid. The surface in the larger Eeles is nearly flat or slightly concave. A small 

 foramen on each side of the basisphenoid in the suture between it and the alisphenoid is 

 the posterior opening of the canal which conducts the Vidian nerve and artery to the 

 foramen sphenoidale : from this proceeds a well-marked groove backwards along the above- 

 named suture, to the foramen lacerum medium ; it then passes along the suture between 

 the tympanic and alisphenoid just outside the foramen caroticum, to the small foramen by 

 which the nerve makes its exit from the petrosal proper, within which bone it branches 

 from the facial nerve. 



When detached the bone in the lion is of the same truncated triangular shape, but it 

 is somewhat wider than was before apparent in consequence of the overlap before described. 

 Its vertical thickness is slightly greater anteriorly than posteriorly, owing to the com- 

 mencement of the upward slope from the bottom of the " sella turcica" to the olivary 

 process within the cranial cavity. The dorsum ephippii rises to a considerable height in 

 all the larger Eeles, and is turned much forwards, the inclination from the summit to the 

 posterior edge of the bone being at an angle of 30° to 35° with the horizontal. The sides 

 of the " dorsum" expand into lateral ala?, somewhat like the wings of a moth, and 

 homologous with the " posterior clinoid processes" in man. The arch formed by them, 

 and the anterior clinoid processes is sometimes completed in Eelis. We have not, however, 

 met with an instance of this in the spelaean skulls : on each side of the " dorsum" is a 

 furrow for the " internal carotid artery." Sometimes there is a small median foramen 

 on the guttural surface, and two minute foramina on the back of the " dorsum 

 ephippii." 



Muscles. — The peristaphyline (Straus-Durckheim) muscle, the representative of the 

 internal muscle of the same name in man, has its origin close to the alisphenoidal suture, 

 at a point where it crosses a line joining the " foramina ovalia." Its office is to lower the 

 " velum palati." The superior constrictor of the pharynx is attached to the posterior por- 

 tion of the bone close to the basi-occipital suture. 



The only point worthy of note in comparing this bone in Felis spelcea with those of 

 lion and tiger is that it has a tendency to be somewhat wider in the two former animals 

 than in the latter. This width, however, is very variable, and cannot be considered 

 characteristic. 



» 



§ 5. Alisphenoid; Pterygoid (Plate VIII, No. 6). — The ahsphenoid, usually described 

 as the ala of the sphenoid, and treated by Straus-Durckheim^ as a mere process of 

 that bone, lies immediately in front of the squamosal in the surface of the cranium. As, 



' Op. cit., vol. i, p. 39.J. 



