REPORT ON THE SEALS. 97 



limb of the Sylvian convolution (syc). The commencement of this limb was at first 

 concealed in the Sylvian fissure, but it became superficial as it passed upwards and 

 forwards ; it then wound tortuously above the apex of that fissure to become continuous 

 with the posterior limb of the Sylvian convolution, which was a broad convolution 

 on the side of the hemisphere behind the fissure and formed a part of its posterior 

 lip. 



The Sylvian convolution was bounded above by the suprasylvian fissure (ss), which 

 arose out of the fissure of Sylvius just before that fissure passed backwards and upwards ; 

 in its course backwards the continuity of the suprasylvian fissure was broken by the 

 passage across it of a bridging convolution ; but it was prolonged downwards and forwards 

 behind and below the posterior limb of the convolution of the Sylvian fissure, where it 

 formed the fissura suprasylvia posterior (ssp), which did not extend into either the 

 Sylvian fissure or the fissura rhinalis posterior. The suprasylvian convolution (ssc) 

 formed the tier above the suprasylvian fissure ; its anterior limb, which lay next behind 

 the praesylvian fissure, passed almost directly upwards and forwards, and then turning 

 backwards became tortuous and was subdivided by short sulci ; but its posterior limb was 

 prolonged downwards and forwards below and behind the Sylvian convolution to join the 

 uncinate convolution, and to form with it the inner end of the posterior boundary of the 

 transverse portion of the fissure of Sylvius. 



The fissura coronalis (co) (Owen), commenced at the outer end of the sigmoid 

 gyrus which it bounded externally ; it was continuous in one hemisphere with about 

 the middle of the praesylvian fissure, though in the other it was separated from it by 

 a short gyrus continuous with the suprasylvian convolution. It was separated by a 

 bridging convolution from the lateral fissure. It curved upwards and inwards, but 

 did not cmite reach the mesial longitudinal fissure, and it formed along with the 

 praesylvian fissure the anterior boundary of the suprasylvian convolution. The 

 fissura lateralis (I) bounded the suprasylvian convolution above, and was continued 

 backwards in a tortuous course and almost reached the posterior border of the 

 hemisphere. 



Between the lateral fissure and the mesial longitudinal fissure two slender gently 

 wavy convolutions passed from before backwards. The most internal of these was the 

 sagittal convolution 1 (sac), which formed the marginal convolution of the longitudinal 

 fissure. It was in part divided by longitudinal sulci into two secondary convolutions, 

 the more internal of which dipped in places into the longitudinal fissure so as to become 

 concealed within it. The sagittal convolution commenced as far forward as the posterior 

 limb of the sigmoid gyrus ; it also bounded the inner end of the coronal fissure, whilst 

 behind it reached the posterior border of the hemisphere and then inclined to the ten- 

 torial surface. 



1 Medial fold of Oweu. 

 (zoou chall. exp. — part Lxvin. — 1888.) Yyy 13 



