Ix Journal of Comparative Neurology. 



large optic vesicles, as two massive ellipsoidal bodies protruding laterally 

 from this region is an early and notable feature. The part which becomes 

 the mid-brain is very early distinguished by its greater breadth and vol- 

 ume. No transverse cerebral folds appear until about four-hfths of the 

 yolk are enveloped. An anterior portion — united mid- and fore-brain — 

 can now be distinguished from the hind-brain. 



The first indication of a true neural canal appears as a fine cleft sep- 

 arating the median cells of the encephalon along a vertical longitudinal 

 plane. At an early stage the brain becomes divided into two flat, thick 

 plates of cells placed vertically between the eyes (Ryder.) At its ante- 

 rior termination the canal sends off two lateral vertical continuations, 

 forming a cruciform fissure which marks off the fore-brain. 



The flexures are described in some detail. A remarkable passage is 

 the following: 



" A small median swelling, not unlike the hypophysis in structure, 

 lies in front of the latter — that is, behind and slightly under the point 

 where the optic nerves decussate. When further advanced such appears 

 to form the hypoaria or lobi inferiores^ — so well developed in Percoids, 

 and their special ventricles in the adult communicate with the lumen of 

 the infundibulum." 



If we understand the passage correctly the authors have certainly 

 wrongly identified the hypoaria anlag. It is probable that the saccus 

 vasculosus and the hypophysis proper have been observed. Histological 

 and histogenetic observations unfortunately are wanting. 



The Dikncephalon of Sklachii and Ami'Hif.ia.i 



Instead of the notice prepared we insert an auto-abstract from the 

 Anatomischer Anzeiger, VII, 15, which will present the points consid- 

 ered most important by the author in his own words. 



The brain of selachians was investigated by means of 25 series of 

 sections from various rays and sharks. Especial advantage accrued from 

 the use of series from various stages of development which made it pos- 

 sible to determine with considerable accuracy the sequence of axis-cylin- 

 der development in different tracts. The diencephalon of various species 

 were first described and this was followed by a comprehensive illustrated 



1. L. Edingeb. TJntersuchungen ueber die Vergleichende Anatoinie rips (ic- 

 hirn.s: 2. Das Zwischenhirn, Part I. Das Zwischenhirn der Selachier iind dcr .\iii- 

 philiien. Abhandlungen der Scuckenht'rtr'.schen naturf. Gesellschaft 



