282 PHYSIOLOGICAL BBMB8, 



con-rant throughout the Carnivora (r/W^ account of ('at'- 

 brain). O.C. i:'.LT) i./. 



.Mi van, Journ. Linn. Soc., vol. xix. 1886, p. 19. 



D. 361. The lirain of a Polar Hear (l'rfnnt maritintus). 



On each hemisphere there is an ansate sulcus joined to 

 the corono-lateral sulcus, as well as complementary ansat.; 

 sulci. There is a simple entolateral sulcus. 



The posterior rhinal fissure appears to join the ursine 

 sulcus in both hemispheres. 



Note that the trape/oid bodies are partly overlapped by 

 thepons. O.C. 



D. 362. A cast of the cranial cavity of a Polar Bear 

 maritimug). 



The exact shape and size of the huge olfactory bulbs and 

 pyriform lobes are clearly shown. 



The great pseudosylvian cleft and all the sulci on the 

 cranial aspect of the hemispheres are admirably demonstrated. 



The examination of a cast such as this enable- u> to 

 appreciate how closely the brain of the extinct Megatherium 

 must have resembled that of Ursus not only in shape but also 

 in the disposition of the pseudosylvian, suprasylvian, orbital, 

 lateral and possibly even the crucial sulci. 



D. 363. The brain of an American Black Bear (Ursus ann'n'r,mux ). 

 In this specimen tin- pnrriu'ial sulci are independent of 

 the crucial sulei, and the hitter do not extend on to the 

 mesial .-urlace. Hence the boundaries of the " Ur>ine 

 lo/.enge" are incomplete. This fact is of interest \\hen it 

 is recalled that certain writers (r/V//- Soury) argue that the 

 ornoial sukms of Carnivores cannoi i-epre>ent tln^ sulm- of 



Kolando, lieeau.M- the former is "e entially a feature of 

 the me-ial surface." 



Tlie ur-ine sulcus is independent of both the calearine 

 sulcus and the rhinal fissure, and extend- into the -ip 

 between these two furrows. 0. (-. l.'Ji'.Vr. 



D. 364. The brain ot an American l>laek I'ear (I V.s//.v ///// rifmiux). 

 The region betwern the lateral suleus and the intei- 

 hemispheral cleft is broken up to an extraordinary d< 

 by numerous irregular gyri. O.C. K'^"> T//. 



