172 KLAUS RUGE 



differentiated. The periamygdalar Corticoid-layer, however, is differentiated ir|| 

 Woodpecker better than in the Wryneck. 



The intercalated cells of the Lamina suprema in Woodpeckers and Wryneckj 

 form a compact zone of small cells. 



The limitation of this cell area to Hyperstriatum accessorium and Hyper- 

 striatum is not distinct. 



The intercaiated cells of Lamina superior are less densely scattered. The celle 

 have their long axis directed in the course of the Lamina. The intercalated cells! 

 of Lamina superior and Lamina suprema are of différent shape. This does not agrée 

 with the opinion of Kappers-Huber-Crosby. Thèse authors suggest that the cells 

 belong to the same cell-type. 



On the other side, at the dorsal ventricular-horn, it appears as if the dorsal 

 cell-mass bends ventrally, continuing in the Lamina superior. The complex of 

 small cells above the dorsal ventriceledge (in Woodpeckers and Wrynecks) I have 

 named Nucleus of the intercalated cells. 



The caudal parts of the forebrain-hemispheres are well developed (Hippo-i 

 campus-Region). We can divide it after Craigie from dorsal to ventral into 

 Parahippocampus, Hippocampus and Primordium Johnstoni. 



In the Hippocampus of Woodpeckers and Wrynecks six vertical zones can 

 be distinguished; in the Parahippocampus of Wrynecks five zones are to be seen, | 

 from latéral to medial: 



1. Zone A — undirected nuclei 



2. a cell-free zone 



3. Zone B — nuclei directed dorso-ventrally 



4. cell-free zone 



5. Tractus-septo-mesencephalicus 



In the Woodpecker the cell-free zones of Parahippocampus can not be 

 distinguished. 



Birds of high évolution show a tendency to reduce the archipallial régions 

 and the cortex. Doubtless Woodpeckers are highly evolved. Nevertheless in the ■ 

 Woodpecker and especially in the Wryneck the hippocampus-formation partici- 

 pâtes essentially in sculpturing the forebrain. 



In Coracioforms — as far as is known — the Hippocampus in no case is as 

 large as in the Wryneck. Only in Hummingbirds {Trochilidae) is the hippocampus- 

 region especially well developed. 



The incubation period in the great spotted Woodpecker is extraordinarily 

 short (shortest time: Dendrocopos major %y 2 -9 days). In the forebrain of the 1 

 newly-hatched Great Spotted Woodpecker not ail striatal régions are differentiated. j 

 The lumen of the ventricle is still large. Commissures are developed but they are 

 not myelinized. In correspondance to the longer incubation period, the forebrain I 



