4 . MR. ST. GEORGE MIVART ON THE 



on one side of the brain of one species. In every case the Sylvian 

 jRssure is embraced by four successive circum- Sylvian convolutions, 

 wbicb, for my present purpose, I shall distinguisb by four simple 

 designations. The two lowest gyri I shall distinguish as the 

 Sylvian gyri (a term already in use), that next the Sylvian gyrus 

 being called the first and the adjoining one above, the second 

 Sylvian gyrus. The third gyrus from the Sylvian fissure I shall 

 designate the parietal gyrus, and the next, and uppermost one, 

 will be spoken of as the sagittal gyrus, since it lies in close 

 proximity to the sagittal crest and suture. In every case I found 

 the two Sylvian sutures well separated and distinct, save on one 

 side of the brain of Icticyon venaticus, where the posterior limb 

 of the first Sylvian gyrus was rudimentary *. Professor Burt 

 Wilder, however, figures seven instances in which he found the 

 separation between the Sylvian gyri incomplete in domestic 

 Dogsf. In every case, without exception, I found the posterior 

 limb of the parietal gyrus to be subdivided by a longitudinal 

 sulcus, so that it bifurcated backwards. Prof. Burt Wilder 

 observes that this bifurcation sometimes extends to the anterior 

 end of the parietal gyrus J. 



In every case I find that there is, on the inner surface of each 

 cerebral hemisphere, a direct continuation of the calloso-marginal 

 sulcus into the crucial sulcus, thus cutting off what is known as 

 the hippocampal gyrus from the sagittal gyrus. In no case do I 

 find, when the dorsum of the brain is looked at, that there is any 

 sulcus proceeding forwards and inwards in front of the crucial 

 sulcus of one hemisphere towards a similarly situated sulcus in 

 the other hemisphere. Nothing of the kind is indicated in 

 any figure of a Cynoid brain which I have seen. Sometimes 

 (as I find in O. Azarcd, G. microtis, and Lycaon pictus) the sagittal 

 gyrus is longitudinally grooved, as is also its inner side in Lycaon 

 and some domestic Dogs. 



■■--1" rioted by Professor Flower in his paper on the anatomy of that 



""5 TK figs. 6 & 7. The number of this speci- 



tions in the Museum of the Eoyal 



'lound, and 20 to 24, Pomeranian 

 Dogs (,me aiiix^— ,£'esented in fig. 20 being the mother 



of those the brains of which are represented in figs. 21, 22, & 23), and, lastly, 

 fig. 25, an EngUsh Terrier. 



I L.c. p. 231, and the figures 12, 21, and 22. 



