314 



DE. G. ELLIOT SMITH ON 



in Oiycteropns. As we trace these bands downward and forward in any Edentate other 

 than Orycteropiis, they will be found to taper and end simply just behi]id the optic 

 chiasma. This mode of ending is shown in the figure of Tamanchia (fig. 10), and Max 

 Weber's figure shows it in Mauls. In his account of the state of the hippocampus in 



Fis. 21. 



hippocamp. nudus 



fascia dentata 



fascia dentata f- 



hippocamp. inversus 



Corp. striat 



fimbria / . ' ^ 



psalterium l'"'^' P^aoonimiss. 



colum. fornicis 



fiss. hippocampi 



Dissection to expose the ventral surfaces of hinder parts of the cerebral hemispheres in Orifcterojnis. 



Enlarged ^ diam. 

 .V. Purrow corresponding to hippoeampo-pallial junction. 



Cholopjms, Flower * mistakes the inverted area of hippocampus for part of the fascia 

 dentata. In many of these brains the inferior extremity of the fascia dentata may be 

 seen, upon the ventral sixrface of the brain, in direct continuity with that part of the 

 pyriform lobe Avhich Gustav lletzius calls the " gt/rus lunaris." This is shown in our 

 figure of 3fi/)-mecophaga (fig. 6), in which the antero-inferior extremity of the fascia 

 dentata makes a peculiar bend toward the fimbria and almost at right angles to the rest 

 of its course. 



In Orycteropus, however, we find, the region of the ventral extremity of the hippo- 

 campal formation occupied by the peculiar large oval swelling which I have called 

 tubei'culwn hiiiiJOcumxn. We may at a glance appreciate the significance of this peculiar 

 structure if we remove the lower extremity of the hippocampal formation from the rest 

 of the brain and examine it from the front, so that we may at the same time see part of 

 the ventricular surface of the hip^iocarajms and the whole of the extra ventricular jiarts 

 (fig. 22). We then see the fimbria descending and rapidly vanishing as a distinct ridge 

 by the scattering of its fibres over the lower parts of the hippocampus. In front of the 

 fimbria we can see the lower part of the ventricular surface of the hippocampus, which 

 we haA^e already seen in profile (fig. 19). We see this alveus-coated surface of the 

 hippocampus sweeping around the lower extremity of the fimbria and becoming extra- 

 ventricular as the tuherculum Idppocampi. The latter structure is obviously nothing else 



* Flower, op. cit., Phil. Trans. 1865. 



