Literary Notices. xxv 



2. If we admit that the number of fibers issuing from the pal- 

 lium affords an index of the quahty or degree of histological perfection 

 of this cortical area, it is obvious that in the Monotremata the cortex 

 must be of poor quality in comparison with that of all other mammals, 

 because the large cortex gives rise to a very small internal capsule, ctus 

 cerebri, and pyramidal tract. 



3. These observations point to the conclusion that, in order to 

 meet the demands which its zoological position and mode of life im- 

 poses upon it, the Monotreme develops a cortex which rapidly increases 

 in quantity, instead of becoming more highly elaborated. 



4. This is especially so in the case of Echidna, which, for an an- 

 imal of its size and lowly status, has an enormous pallium, which ex- 

 hibits numerous sulci. But it is a very significant fact that the arrange- 

 ment of these sulci does not conform to the plan which, with relatively 

 slight variations, prevails throughout the large group of Meta- and 

 Eutheria. 



5. The features of the pyriform lobe, the tractus olfactorius, and 

 \}[\^&fi5sura rhinalis are quite distinctive. 



6. The fact that the supra- and precommissural parts of the hip- 

 pocampal arc (especially in Ornithorhynchus) are larger and better 

 developed than the descending part of the arc, is distinctively Pro- 

 totherian. 



7. The absence of a projecting fimbria and the attachment of the 

 choroidal fold at the margin of the fascia dentata are unique features. 



8. The round or oval shape of the commissura dorsalis (vel hippo- 

 campi) in sagittal section is characteristic of this order. 



9. The attachment of the roof of the fore-brain to the anterior 

 lip of the thickened upper extremity of the latnina terminalis so as to 

 form a supracommissural diverticulum of the third ventricle {recessus 

 superior), is a significant feature which may be shared by some marsu- 

 pials {Didelphys? Perameltst Notoryctesl Phascolarctosl), but is certainly 

 not common to all the marsupials. 



10. In comparison with the size of the cerebral cortex, the potis 

 Varolii is small. 



1 1 . The lateral parts of the cerebellum are small, and those 

 regions of the cerebellum which in the Eutheria show a progressive in- 

 crease in size and complexity are peculiar in the Monotremes, by rea- 

 son of their diminutive proportions and the paucity of fissures. 



12. The plan of the cerebellum in the Monotremes is in marked 

 Eutheria {yide " The Brain in Edentata," Trans. Linn. Society, Lon- 

 don, 1898). 



