Kappers, Telcostean and Selachian Brain 23 



part of the brain and ends in the hypothalamus, a course similar 

 to that of the tractus olfacto-loharis lateralis. This tract is col- 

 lected from almost the same region where the tractus olfacto- 

 habenularis originates, but from a more extensive area. Its 

 unmedullated fibers go into the most dorsal part of the lateral wall 

 of the praethalamus. That it should then give off fibers for the 

 anterior part of the corpus geniculatam laterale, as Herrick 

 supposes, I think not probable for Gadus. Thereupon it runs 

 with little inclination ventrad so that after a short distance it meets 

 the tr. olfacto-loharis medialis, which it almost entirely enwraps 

 (Fig. xl). Since, however, the latter terminates in the lobi 

 inferiores before the former, this afterward passes on alone and 

 ends (Figs, xlv, xlvi) after decussation in the posterior part of 

 those lobes partially under their ventricles. This might be the 

 same tract which Haller describes as a pallial part of the tractus 

 strio-thalamicus which also decussates in the hypothalamus. 



Among the olfactory connections I have still to treat of the 

 tractus olfacto-habenularis which was also mentioned in the first 

 chapter. This bundle consists of medullated fibers of much 

 smaller caliber than those of the tr. olfacto-loharis lateralis, in 

 company with which it originates, though in a somewhat more 

 ventral area. It runs along the dorso-lateral side of the latter 

 tract and at once upon reaching the epithalamus, where it is 

 situated immediately adjacent to the tectum opticum which here 

 covers the epithalamus dorso-laterally, it enters the most anterior 

 and dorsal ganglion of the ganglia habenulae, joining the com- 

 missura habenularis (Figs, xxvii and xlii) which connects the 

 ganglia. The area olfactoria posterior lateralis, being situated 

 at about the same height as these ganglia and being quite near to 

 them on account of its inclination backward, this tract is very 

 short, which perhaps is the reason that some authors meet with 

 great difficulty in finding it. 



Thus the olfactory areas of the fore-brain are connected by one 

 tract with the epithalamus and by two with the lobi inferiores. 



The most ventral part of the praethalamus contains the fibers 

 originating from the striatum and. going to the lobi inferiores, the 

 tractus strio-thalamicus, known now for many years. This large 

 feebly medullated bundle passes backward laterally from the 

 tractus praethalamo-cinereus and under the tracts last described 

 almost in a straight line under the corpus geniculatum laterale. 



