308 'Journal of Comparative Neurology and Psychology. 



former pupil Mr. P. S. McKibben, to whom I am also greatly 

 indebted for assistance in other ways. 



Morrill has figured an excellent dissection of the organs here 

 under consideration in Prionotus carolinus, and also the histo- 

 logical details of the peripheral terminations of these modified 

 spinal nerves; but the central connections of these nerves have 

 not been analyzed microscopically so far as I know. 



In Fig. I is given a sketch of the external form of one of my 

 alcoholic specimens as seen from the left side. The spinal cord 

 caudad of the so-called accessory lobes is considerably larger than 

 is usual among the teleosts, the enlargement being confined chiefly 

 to the dorsal and lateral parts (Fig. 2). The ventral funiculi and 

 ventral commissure are as usual. The tractus spino-tectalis (fas- 

 ciculus lateralis, Mayser, the tract which is continuous ceph- 

 alad with the lemniscus of my nomenclature in former papers) 

 is well-defined, but not greatly enlarged, immediately behind the 

 accessory lobes; farther caudad it ca'n with difficulty be distin- 

 guished from the adjacent fasciculi proprii. The latter region 

 is enlarged and filled with fine medullated longitudmal tracts 

 (fundamental lateral tracts). Farther laterally the ventro-lateral 

 and dorso-lateral fasciculi are still more greatly enlarged, the 

 fibers being larger and with denser sheaths, especially dorsally. 

 The dorsal cornu and dorsal funiculus, which are very small in 

 most telecosts, here comprise nearly one-half the total cross-section 

 of the spinal cord. This region is made up of small bundles of 

 medulated fibers separated by dense masses of unmedullated 

 fibers or neuropil. Strong tracts pass obliquely laterally and 

 ventrally between these masses and the dorso-lateral fasciculus 

 and more diffuse fibers, chiefly unmedullated, to the fasciculi 

 proprii (formatio reticularis) and dorsal commissure. At inter- 

 vals, also, bundles of medullated fibers pass along the extreme 

 external surface between the dorsal and ventral funiculi. These 

 are uncrossed. 



The longitudinal tracts in the dorsal funiculi are mostly short 

 paths. Individual bundles as a rule do not long remain distinct, 

 and medullated tracts leave them at frequent intervals to enter 

 the fasciculus dorso-lateralis, where they appear to turn caudad, 

 for the latter fesciculus increases in size and compactness for a 

 time as it passes backward. Ultimately, however, it blends with 

 the adjacent fasciculus ventro-lateralis and fasciculus proprius. 



