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The course of the very small tractus olfactoriiis medialis pars 

 medialis does not differ from that in Cjprinns, while on the other 

 hand, the thick meduUated tractus olfactoriiis medialis pars lateralis 

 takes a different course. According to Sheldon (6), Kappers (4), 

 Goldstein (1), and others, this bundle decussates with the commissura 

 anterior in at least the large majority of cases among Teleosts. In 

 Synbranchus and Monopterus, however, nothing is to be seen of 

 this decussation. The tract here runs somewhat in a lateral and 

 dorsal direction, on to the commissura anterior, and then penetrates 

 between the various bundles of the tractus strio-thalamicus (tig. 4). 

 When slightly lateral from this, i. e. dorsal from the fissura endor- 

 hinalis, the bundle dissolves into a dense network of fibres which 

 lie nearly on the boundary of the nucleus piriformis, the striatum 

 'and the ventral portion of the septum (fig. 5). The fibres of this 

 network then spread into the nucleus piriformis and the nucleus 

 taeniae, which are not clearly distinguishable from each other here, 

 and further into the caudal part of the epistriatum. This region, 

 behind the sulcus ypsiliformis, is thus provided with olfactory fibres 

 only by the lateral part of the median olfactory tract. 



Very slightly caudal from the place where the tractus olfactorius 

 medialis pars lateralis merges into the aforesaid network, medul- 

 lated fibres from the nucleus piriformis gather (Goldstein's com- 

 missura olfactoria intern uclearis, described as a non-medullated 

 bundle by Sheldon under the name of tractus olfactorii mediales 

 partes laterales). These fibres, forming a considerable bundle, decus- 

 sate with the most posterior part of tho. commissura anterior (fig. 4). 

 It is possible that in this bundle there are still a few decussating 

 fibres, of the tractus olfactorius medialis pars lateralis; but this I 

 could not* determine with cei-tainty. 



In connection with the coalescence of the two halves of the fore- 

 brain, the course of a part of the so-called tractus strio-thalamicus 

 is very remarkable. The majority of the fibres which form this 

 bundle congregate, as in all Teleosts, from nearly every part of the 

 fore-brain and, after having decussated partly in the commissura 

 anterior, run medially from the fissura endorhinalis to the mid- 

 brain. From the most posterior part of the epistriatum (the lingua 

 posterior), however, a great number of medullated fibres join to 

 a thick bundle, which decussates somewhat further frontally in the 

 median striatal portion connecting the two halves of the telencephalon, 

 (fig. 4). After the decussation this bundle runs a short distance 

 forward in the dorso-lateral portion of tlie striatum. On the frontal 

 level of the commissura anterior this bundle bends at a right angle 



