Wilder.] 04Z j-j^ly 15^ 



C. A LIST OF SOME POINTS TO BE ELUCIDATED. 



Ko part of the cat's brain is thoroughly or sufficiently understood, and 

 all parts need monographic treatment. The following points, therefore, are 

 selected because the deficiencies in our knowledge of them have been most 

 distinctly impressed upon me. 



Albicans. ■ — abn. — Have the albicantia the same relation to the Columnse for- 

 nicis which is said to exist in the human brain ? "What morphical or telical 

 significance has their degree of separation from one another ? 



Area elUptica. — Ar.,el. — ^With what does this correspond in man and the 

 lower vertebrates ? If it represents the ofoca or " olivary body, " its position 

 is reversed from that in man in relation to the appai'ent origin of the N. 

 hypoglossus. 



Area ovalis.^Ar. ov. — With what does it correspond in man and the 

 lower vertebrates ? What are its relations to the several columns of the 

 myelon and metencephalon 1 



Aula. — a. — What are its precise limits ? In the cat, and other forms with 

 a large medicommissura, this commissure may be regarded as its caudal 

 boundary ; but in man, where the commissure is smaller, and in the lower 

 vertebrates where it is wholly absent, the question of limitation is more 

 difficult. 



Auliplexus. — apx. — The plexus which appears near the dorsal end of the 

 aula on each side. This, plexus is continuous, through the portiplexus, 

 with the proplexiis, and apparently also with the diaplexus, but the rela- 

 tions of the latter are doubtful. 



As to the plexuses in general, are they formed as stated by Quain (A, 

 II, 545), and other authors, by the intrusion of the free border of the 

 velum, or of processes thereof, still covered by the endyma, into the 

 various cavities, or as recently stated by Mivart (B, 266) ? 



"The choroid plexuses of the lateral ventricles are (like those of the 

 third) merely portions of the ependyma, which happen to be very vascular, 

 and are not really intrusions from without." 



This statement is so positive that, though unsup|)orted by figures, or 

 detailed description, I forbear to affirm the contrary. So far as I can judge, 

 however, the proplexuses are intrusions of the pia, while the diaplexuses 

 seem to correspond more nearly with the view of Mivart. In the one case, 

 the fold of velum bears to the fold of endyma the same relation which an 

 abdominal viscus bears to the visceral layer of peritoneum ; in the other 

 case, the plexus may be compared to a fold of omentum. 



Carina (fornicis). — ca. f. — How nearly constant is it, and what is its sig- 

 nificance ? 



Cauda {striati). — cd. s. — Is it distinct in the cat? Has it the relations des- 

 cribed in man by Cuvier (B, III, 51), and others, and more recently and 

 fully by Dalton (1, 13) ? 



Spitzka says (7) : — 



"I have identified this structure in the cat ; it does not make as fine a 

 sweep as in man, but is distinct at the roof of the inferior horn and loses 



