310 'Journal of Comparative Neurology and Psychology. 



of some of the shallower furrows. That they are really enlarge- 

 ments of the dorsal cornu and not adventitious structures is shown 

 by their continuity caudad with these cornua, and by their rela- 

 tions with the dorsal roots which supply tactile sensibility to the 

 free pectoral fin rays, and also by their secondary connections. 



These outgrowths evidently arose from the dorso-lateral border 

 of the spinal cord and then from broad pedicles at this point 

 spread in mushroom form both mesially and laterally (Fig. 3). 

 The enormous dorsal root of the third spinal nerve enters the 

 lateral border of the fourth, fifth and sixth lobes and terminates 

 within them. 



Secondary tracts in large heavily medullated bundles pass from 

 these accessory lobes ventro-laterally to descend in the fasciculus 

 dorso-lateralis. The greater part of this tract caudad of this 

 point is apparently derived from the sixth lobe, only a small pro- 

 portion of the descending fibers of this tract coming from the spinal 

 cord farther toward the head. Very large tracts of medullated 

 fibers pass in the fasciculus dorso-lateralis between the fifth and 

 sixth lobes, which are separated by a wide and deep furrow ( Fig. 4 ) . 

 The dorsal commissure contains massive bundles of medullated 

 decussating fibers in the inter-lobar spaces as well as in the regions 

 of the lobes. These fibers run between the lobes and the opposite 

 dorsal and dorso-lateral tracts. 



As we pass cephalad under the fourth and fifth accessory lobes, 

 the relations of the funiculus ventralis are little modified; the dorsal 

 and ventro-lateral fascicles are somewhat enlarged; and the dorso- 

 lateral very greatly so. This enlargement is due partly to fibers 

 which run between the fifth and sixth lobes and also to large 

 bundles of root fibers, which pass toward the head to end in the 

 fourth and fifth lobes. These lobes, like the others, send tracts 

 of medullated fibers downward to the ventral cornua and ventro- 

 lateral fasciculi of the same side. 



Between the fourth and third lobes (Fig. 5) the dorso-lateral 

 funiculus shrinks to small dimensions — scarcely larger than in 

 some other fishes, like Ameiurus. The tract which I have termed 

 the funiculus dorsalis, however, maintains its large size. From 

 these relations of the dorso-lateral fasciculus, which is evidently 

 the chief path of communication between these tactile centers of 

 the spinal cord, it appears that the fourth, fifth and sixth lobes, 

 which receive the dorsal root of the third spinal nerve, constitute a 



