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and the more dorsal epistriatum. These two grooves together may 

 thus very justly be termed the sulcus palaeopallio-epistriaticus, as 

 this has been described by Kappers and Theunissen (5) in Thynnus. 



The most posterior portion of this groove is verj' deep and 

 narrow; the boundary between the palaeopallium and the epistriatum 

 can therefore be drawn very sharply there. The direction of this 

 portion is almost caudo-frontal. Towards the front, the groove 

 becomes shallower and wider. It then deviates in a ventral direction 

 and leaches the fissura endorhinalis on the front of the hemispheres, 

 getting gradually fainter. 



Dorsally from this sulcus palaeopallio-epistriaticus there lies a 

 body which I take to be the epistriatnm (the primordium hippocampi 

 of Sheldon). At least the posterior portion, limited by the deep 

 grooves, corresponds exactly in form to the epistriatum of Gadus, 

 Silurus and other tishes, as has been described by Kappers. Thus 

 it shows clearly a lingua lateralis descending in the sulcus ypsili- 

 formis, as well as a lingua posterior projecting backwards. The 

 latter is especially distinct in Synbranchus (fig. 6). This part too 

 receives secondary olfactory fibres from the tractus olfactorius 

 medialis pars lateralis, just as the lateral part of the hemispheres 

 lying caudally from the sulcus ypsilliformis. To this very pronounced 

 part of the epistriatum an anterior portion joins, which is connected 

 with it by a narrow strip lying rather deeper, so that one might 

 say that it is separated from it by a broad and shallow groove. 

 Viewed through the microscope, these two parts merge invisibly 

 into each other. I therefore believe that this front portion must 

 also be considered as a part of the epistriatum. Like the caudal 

 portion it is closely connected with the palaeopallium. Both receive 

 secondary olfactory fibres from the tractus olfactorius lateralis. On 

 the other hand, it is fairly sharply divided from the striatum, over 

 which it lies like a hood. 



The epistriatum is bounded on the median side by the sulcus 

 limitans telencephali, which has been described by Sheldon, and 

 which forms, the boundary between the corpus precommissurale 

 (septum mihi) and the primordium hippocampi of this author 

 (epistriatum mihi) (figs. 1, 2, 3, 4, 5, 6). This sulcus in Monopterus 

 is very narrow and deep, as is seen in figs. 3, 4, and 5, specially 

 the posterior portion of the epistriatum (the lingua posterior) is 

 sharply separated by it from the other parts of the hemispheres. In 

 Synbranchus the sulcus is not so deep, but this is secondary 

 compared with Monopterus, since, here and there in Synbranchus 

 a series of ependyma cells is found lying between the epistriatum 



