212 PROCEEDINGS OF THE AMERICAN ACADEMY 



Few of these points are of much consequence. We might dismiss 

 the brain with the statement that the frontal region is largely devel- 

 oped and complicated and the rest simple, were it not for the very rare 

 anomaly about to be described. This is a small gyrus uniting the two 

 central convolutions by dividing the fissure of Rolando. It occurs on 

 both sides of the brain. On the left, it is situated about one inch from 

 the median fissure, and runs obliquely forward and upward from the pos- 

 terior to the anterior central convolution. It is superficial throughout 

 and absolutely unmistakable. On the right, it is much less easily recog- 

 nized : for, though superficial, it is very near to the median fissure, and 

 at first suggests simply a somewhat premature ending of the fissure of 

 Rolando; but a glance at the inner side of the hemisphere shows that 

 this view is not tenable, — that there is actually a bridge, and that the 

 fissure is even a little longer than usual. The termination of the 

 calloso-marginal fissure is a useful guide in studying these relations. 

 "When the writer examined this brain, there was but one case of this 

 anomaly on record; and this, curiously enough, was in the. brain of a 

 known man, that of Dr. Fuchs, of Gottingen, which is described by 

 Wagner.* " Both [i.e., the central convolutions] are connected with 

 one another by bridges, of which, especially on the left side, a very 

 considerable one arises, with a broad root, from the anterior central 

 convolution." It will be seen by consulting Wagner's plates that the 

 gyrus on the left side of Fuchs's brain is very similar to tiie one de- 

 scribed in this paper. Bischofff refers to Wagner's statement in a 

 tone approaching that of unbelief. He writes : "These two convolu- 

 tions [the central ones] have always two communications around the 

 ends of the fissure, bordering on the great median fissure and on the 

 Sylvian fossa, but never in their course. It is very striking that R. 

 Wagner should describe and figure such a communication between 

 both central convolutions on the brain of Professor Fuchs, as if it were 

 something of frequent occurrence. In the many brains that I have 

 examined, I never saw any thing of the kind"." And, again, Bischoff, 

 speaking in another place of the same fissure, says,'* Which [the fissure] 

 is distinguished from all other fissures by its early appearance, its un- 

 changed direction and structure, and the fact it is never interrupted by 

 any convolution, and only ver)' gradually inclines rather more backward." 

 And ai'ain, in discussing this fissure in apes, " Its course in apes also is 



* Vorstudien zu einer wissenschaftlichen Morphologie und Pliysiologie des 

 mensclilichen Geliirns als Seelenorgan. 1860-62. 

 t Die Grosshirnwinduugen des Menschen. 1868. 



