116 



Dr. E. Schuster. Cell Lamination of the [Sept. 30, 



or bulb. The greatest depth of the fissure is 7 or 8 mm., but the incision 

 referred to is 9 mm. deep. 



Fissura rhinica posterior {frhp) runs at first basal wards, then turns 

 horizontally backwards, and describes finally a flat curve with its concavity 

 directed downwards. Its posterior segment, sometimes separated from the 

 main division, cuts the posterior mesial border of the hemisphere. The 

 depth in the anterior division is about 7 mm., but gets considerably less 

 posteriorly. 



Fissura postsylvia anterior {/psa) [Elliot Smith, «] approaches the sylvian 

 fissure at its lower end in a characteristic manner ; it runs upwards and 

 backwards and cuts the mesial border of the hemisphere 25 mm. from the 

 frontal pole. It may be straight or wavy, but there is always an angular 

 bend in the middle third from which a posteriorly directed side branch is 

 given off. The depth is between 2|- and 4| mm. 



Fissura postsylvia posterior (fpsp) lies 6 mm. behind fpsa ; it cuts the 

 border of the hemisphere behind the occipital pole, i.e. behind the point 

 where the border runs laterally outwards. The fissure runs continuously 

 downwards and forwards as far as the angle of fpsa, but in front of this its 

 direction is continued by an anterior segment. The main fissure is called 

 f. postsylvia posterior occipitalis (fpspo) [Elliot Smith, f], and is 2^ mm. 

 deep. The anterior segment is called f postsylvia posterior temporalis 

 (fpspt) [Elliot Smith, 77], and is 1| mm. deep. Occasionally another fissure, 

 f. postsylvia postrema, is present behind and parallel to fpsp. 



Fissura antesylvia posterior (fasj)) [Elliot Smith, ^] is the most constant 

 of the fissures in the anterior part of the brain ; it lies parallel to fpsa, 

 2 to 6 mm. in front of it. Wlien well developed its lower end lies over the 

 sylvian fissure. In this region it often turns sagitally forwards and may be 

 forked. Its depth may reach 3 mm. Between it and fpsa there may be 

 another fissure. 



Fissura antesylvia anterior (fasa) [Elliot Smith, 7 and 8) lies })arallel to 

 and in front of fosp. It is sometimes as well developed as the latter, and 

 cuts deejjly into the mesial border of the hemisphere. More often it is 

 weakly developed, failing to reach the border and sometimes falling into two 

 pieces. Its lower end may be forked, depth to 3 mm. 



Fissurce frontomarginales superior and inferior' (ffs and ^t) [Elliot Smith, e] 

 lie in front of fasa ; thoy are very varialjle. 



On tlie median surface of the l)rain may be found the Fissura hippocampi 

 (FIJ) which follows the characteristic course of the hippocampus, starting in 

 the upper anterior part of the l)rain, running backwards and then curving 

 downwards and finally forwards, to end somewliero below its starting point. 



