. Anatomischer Anzeiger. Anatomy, Comparative. 122 verse section through this formation in the region indicated above (i. e. in front of the commissures) the hippocampus may be seen to form the dorso-mesial angle of the hemisphere. The appearance of this region in the black snake (Pseudechis) is represented in a purely schematic manner in Figure 1. Hippocampus Fascia dentata. Precommissural area Pig. 1. Scheme of hippocampal formation of a Reptile (Pseudechis) as seen in transverse sec- tion in front of the region of the commissures. Upon tracing it downwards upon the mesial wall of the hemi-
. Anatomischer Anzeiger. Anatomy, Comparative. 122 verse section through this formation in the region indicated above (i. e. in front of the commissures) the hippocampus may be seen to form the dorso-mesial angle of the hemisphere. The appearance of this region in the black snake (Pseudechis) is represented in a purely schematic manner in Figure 1. Hippocampus Fascia dentata. Precommissural area Pig. 1. Scheme of hippocampal formation of a Reptile (Pseudechis) as seen in transverse sec- tion in front of the region of the commissures. Upon tracing it downwards upon the mesial wall of the hemi- sphere, the characteristic histological structure of the hippocampus will be found to cease abruptly and give place to the precommissural area, from which it is separated by the fornix fibres. Throughout this simple hippocampus consists of four layers: 1) a thin white medullary layer next to the ventricle — the so-called alveus; 2) a layer of scattered polymorphous cells; 3) a very regular lamina of closely packed cells and 4) the molecular layer. The third layer (3) on the dorsal aspect of the brain consists of large pyramidal cells, with large cell bodies. As it is traced on to the mesial aspect these large cells gradually [in fig. 1. the change is represented as abrupt] give place to a dense mass of smaller and more closely packed cells, so-called "granules". The latter constitute the stratum granulosum of the Fascia dentata; while the pyramidal cells are the homologues of the "layer of pyramids of the cornu Am- monis — the lamina grigia circonvoluta" of Golgi1). Although Spitzka 2) and Edinger 3) have located the hippocampus 1) loc. cit. 2) Journal of nervous and mental Diseases, 1880, and Science, 1880 — quoted by Beill (vide infra) and Stbasser (loc. cit.). 3) "Biechapparat undtAmmonshorn". Anatomischer Anzeiger, Jahrg. VIII, No. 10, 8. April Please note that these images are extracted from scanned page images that may have been
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