292 PHYSIOLOGICAL SERIES. 



The features of the Sylvian region essentially agree with 

 those of Otaria (figs. 164 & 166). We can, however, 

 recognise in the submerged area more definite traces of 

 the ectosylvian sulci than in Otaria. They are found in a 

 position analogous to those of the Bear (D. 360). 



The anterior limb of the suprasylvian (" ectosylvian " of 

 Ziehen) sulcus is submerged, and can be exposed only by 

 drawing forward the anterior lip of the Sylvian fissure 

 (fig. 164). It emerges at the apex of the Sylvian tissure, 

 and, after giving off a short vertical branch, bonds back- 

 ward for about an inch, and then passes freely into con- 

 tinuity with the vertical postsylvian ; the latter pursues a 

 course exactly like that of Otaria (compare figs. 161 & 164). 



A large vertical branch proceeds from the junction of 

 the suprasylvian and postsylvian sulci. 



As in Otaria, the region between the postsylvian and the 

 pseudosylvian sulci is much broken up by a series of oblique 

 sulci. 



The great vertical coronal sulcus passes freely into the 

 lateral sulcus. The latter is not joined to the large vertical 

 postlateral sulcus. There is a great oblique sulcus be- 

 tween the crucial and the lateral sulci ; it corresponds to 

 the dorsal prolongation of the marginal sulcus in Otaria, 

 but is to be regarded also as a compensatory ansate. The 

 ansate sulcus is very small, and, as we have seen in the 

 Bear's brain, we should expect to find a large compensatory 

 series of sulci in this situation. 



We find a deep entolateral (or paracalcarine) snlcu 

 in Otaria and the Ursidae. Its lower part is represented 

 by a separate sulcus, parallel to the postlateral on the 

 cranial surface. 



There is a well-defined " Ursine sulcus," which is pro- 

 longed laterally between .the postsylvian and postla 

 as in Otaria. 



There is a great, deep, vertical calcarine, which becoi 

 forked at its ventral extremity; in other words, the com- 

 pensatory ralrarine (analogous to the Primate collateral) 

 sulcus opens into it. 



There is a postcalcarine branch, as in Otaria. 



