817 



fiinclionallv it is analogous to but upon a lower plane of usefulness 

 than tlie neopallium", (op. cit. p. 272). He lias established the 

 truth of this statement for Reptilin in general by reference to 

 examples of the Ophidia, Lncertilin, and Chelonia. Moreover, he 

 points out, that the evidence now goes to show that every mam- 

 malian brain passes through a stage of development in which the 

 corpus striatum is clearly divisible into hypopallium and palaeo- 

 striatum. Subsequent development shows that the hypopallium in 

 man gives rise to the putamen and most of the caudate nucleus 

 (together constituting the neostriatum of Ariëns Kappers), the claustrum, 

 and the hypopallial element of the nucleus amygdalae. The palaeo- 

 striatum forms the globus pulUdiis and according to Elliot Smith 

 a small part of the caudate nucleus (op. cit. p. 291 ; vide however, 

 Ahiëns Kappkks 1922, p. 153). 



In Sphenodon the boundary line between the hypopallium and 

 palaeostriatum is indicated by the course of large arterial vessels 

 and emerging veins, the former constituting the lateral striate artery 

 of reptiles, (Elliot Smith op. cit. p. 272). 



Shelt.sheak (1920) has identified this artery in the adult human 

 brain immediately lateral to the palaeostriatal area and has called 

 it the claustral (or hypopallial) artery. It seems that, in conformity 

 with the phyiogenetic and ontogenetic history of the pallial origin 

 of the hypopallium, pallial vessels have become hypertrophied at 

 the site of intilting of the pallium to supply this new pallial develop- 

 ment. Deeply penetrating into. the hemisphere they form in man a 

 lateral group of the antero-lateral ba.sal vessels of the middle cerebral 

 artery. 



The vascular supply of the corpus striatum of Apteryx presents 

 some remarkable features. In the first place a series of large vessels 

 enter the liase of the hemisphere in the fissnra ventralis {jissura 

 Umbica, Edingi-.h) and penetrate deeply into the corpus striatum 

 (Fig. V). The course of these arteries follows very closely that of 

 the external medullary lamina; in other words they form a clear 

 line of seperation between the hyperstriatum laterally and the meso- 

 striatum medially. This arrangement is constant even in the most 

 posterior region in which the external medullary lamina can be 

 identified and the separation of the mesostriatum from the hyper- 

 striatum distinguished. Medial to this fissure many smaller vessels 

 penetrate the corpus striatum in the region of the jialaeostriatum 

 and the blood supply is considerably from this source, (cf. Owen 

 1872, p. 381). 



In contrast with this the blood supply entering the corpus striatum 



