814 



Fiirtlier caiidallj tlie ventricles iiiciease iii size being less reduced 

 by tlie eiici'oaclimeiit of the corpora striata lateraiij (Fig. IX— XI V)- 



The criterion of cell structure (cf. Rosk, 1914) cannot be employed 

 in analysing the constitution of the corpus striatum in this instance 

 on account of the poor stale of preservation of the specimen. For 

 this purpose it becomes necessary to rely upon (ibre connections 

 and topographical relations in differentiating its various parts. In 

 naming these the nomenclature of Edingek (1896) will be followed. 



Fortunately the nvclens entopednnciilnre can be recognised at the 

 junction of the telencephalon and diencephalon. Surrounding this 

 nucleus is a large-celled area forming ihe nticleus hasalis i^ottsüiuting 

 the iialiieoslriatuin /irimitivinn (Ahiëns Kappkrs, 1908; 1922). This 

 is surrounded by a lai'ger part of the striatum which is an extension 

 of the palaeostriatum — the mesostriatum or palaeostriaiitm aug- 

 nientatiun, (Ahiëns Kappers, 1922, [t. 140). The lainina medtiUavis 



Tr. Sep mcs.x 



Trolf.hab.' / / 



Ir ot.rties, 



Rg.X 



ventralis (lamina medulhiris interna of Kappers, op. cit.) which 

 separates these two parts from one another is not to be seen in the 

 sections at hand. 



If the sections showing these areas be examined (Fig. VI— VII) it is 

 very evident that dorso-lateral to the mesostriatum there lies a mass 

 of considerable size constituting the hyperstrialum. Its extent is as 

 follows. Dorsally it is sei)arated from the cortex by an ill defined 

 lamina of fibres {cnpsuln externa of Edinger, Wallenberg and 

 Holmes, op. cit. p. 365 ; Taf. V). Traced laterally and ventrally it 

 becomes continuous with the external or pallial surface. This mass 

 is separatetl from the mesostriatum by a layer of fibres which 

 constitute the lamina medulhiris dorsalis (cf. Edinger, Wallenberg 

 and Holmes op. cit. p, 390; Schhoeder, op. cit. p. 141). This sub- 

 division is exceptionally clear in Apteri.r. This is partly due to the 



