618 E. H. J. SCHUSTER. 



Sulcus arcuatus {arc). — From tliemosfc posterior portion 

 of the backwardly directed convexity of this fissure a straight 

 branch runs upwards and backwards. The upper limb in the 

 right hemispliere is uniied at its extremity with one of the 

 sulci oi: tlie frontalis superior series. The lower limb in both 

 hemispheres runs straight downwards and forwards, and ends 

 about a centimetre above the anterior end of the Sylvian 

 fissure. 



Sulcus inferior transversus {it.) runs obliquely 

 upwards and forwards between the lower ends of the sulcus 

 centralis and sulcus arcuatus; in the right hemisphere it is 

 connected with the Sylvian fissure. 



Sulcus rectus {rect.) runs horizontally forwards from a 

 position about 5 mm. in front of the sulcus arcuatus, to end 

 about the same distance from the frontal pole. Between its 

 posterior end and the lower portion of the sulcus arcuatus 

 lies the sulcus diagonalis {d.), a shallow oblique fissure 

 better marked in the right hemisphere than in the left. 



The sulcus pra?cen trails superior and sulcus 

 frontalis superior {fs. 1, 2, S, 4) Jii'e together repre- 

 sented by a series of shallow fissures, of which the posterior 

 {fs.^ is the best developed. This lies in a more or less 

 sagittal direction, while the other members of the series are 

 more ti'ansversely placed. 



On the orbital surface is found a sulcus orbital is [orh.) 

 lying near the mesial border; this is triradiate in the right 

 hemisphere, but a simple, more or less sagittal, fissure in 

 the left. On the lateral side of this is the obliquely placed 

 sulcus frouto-orbitalis (/o.), the anterior outer end of 

 which just reaches the lateral surface of the hemisphere. 

 This fissure is quite well defined, though not more than three 

 or four millimetres deep. Its shape is complicated in the left 

 hemisphere by the presence of a shallow forwardly directed 

 bifurcated branch. 



The sulcus temporalis superior (T.v.) is a long, well- 

 developed fissure extending both in front of and behind the 

 Sylvian fissure. Its posterior end is bifurcated in the right 



