MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 263 



border. On the upper and mesial side they are directly continuous with the anterior, 

 posterior and inferior lobes. On the outer side, however, they are separated from 

 these by the prolongation of the fissure of Sylvius backward. Of the lower or inferior 

 lobe, he only remarks that it lies in the middle cranial fossa, but of its posterior 

 boundary he says nothing. The posterior lobe is bounded on its inner surface 

 anteriorly by the Hinterspalte (fissura parieto-occipitalis) . On the lateral surface it 

 approaches nearly to the cleft of the Sylvian fossa. Of a boundary on the lower 

 surface, he merely remarks that it lies on the tentorium above the cerebellum. He 

 seemed to think that these divisions corresponded to the contained nervous matter 

 of three cranial vertebrae, and he stated that the divisions of these lobes corre- 

 sponded in the human brain to the regions covered by the frontal, parietal and 

 occipital bones. Bischoff has shown, however, that this is not so, and that the 

 limits of these bones both in Man and the lower animals does not bear any constant 

 relations to the contained brain. 



Krause, in his Anatomy, pp. 1,000-1,008, accepts these divisions of Burdach. 

 Of the posterior lobe, he remarks that on its lower surface it is bounded by a 

 shallow furrow corresponding to the upper angle of the pyramid of the petrosal 

 bone. Valentin, following Sommering, likewise accepts Burdach's division. The 

 posterior lobe, he says, covers the middle and posterior part of the small brain and 

 forms the hindmost part of the hemisphere, and he states that it corresponds in 

 extent to the upper part of the supra-occipital bone. 



Arnold 1 distinguishes five lobes : 1. The anterior or frontal lobe is separated 

 by the fissure of Sylvius, on the outer side posteriorly by a perpendicular fissure 

 (fissura centralis) and superiorly corresponds with the frontal bone, with the 

 exception of the most posterior part of the same, which extends beyond and covers 

 part of the next lobe. 2. The parietal lobe is covered by the posterior part of the 

 frontal and by the larger anterior portion of the parietal bones. It is bounded 

 anteriorly by the perpendicular fissure mentioned above, and inferiorly by the fis- 

 sure of Sylvius. 3. The occipital lobe corresponds with the posterior part of the 

 parietal bone and with the upper half of the occipital scale (supra-occipital) 

 passes forward and downward without distinct separation into the temporal lobe, so 

 that it seems as though it were a prolongation of the latter. 4. The lower or 

 temporal lobe occupies the middle cranial fossa, one on each side, and is separated 

 anteriorly by the Sjdvian fissure and above by the horizontal prolongation of the 

 same. 5. The stem lobe or island of Reil. Arnold was the founder of these five 

 divisions which were afterward adopted by Gratiolet, except that he terms the 

 island of Reil the central lobe (lobus centralis) and the temporal lobe, temporo- 

 sphenoidal. 



Huschke 2 followed no definite principle in dividing the cerebrum into lobes. 

 Although he doubts that the brain has adapted itself to the skull but rather the 



1 Haudbuch der Anatomie. 



2 Schiidel, Hirn, etc. 



33 JOURN. A. N. S. PHILA., VOL. X. 



