41 6 'Journal of Comparative Neurology and Psychology. 



developed at this level. The first part of the commissure con- 

 tains, in addition to the acoustic commissural tract above described, 

 more numerous finer fibers which connect the lateral funicular 

 nuclei and the underlying dorso-lateral fasciculi (figs. 7 and 8). 

 Even as far back as the first dorsal spinal root (fig. 8) the somatic 

 centers are not greatly enlarged except the lateral funicular nucleus. 

 The lateral funicular nucleus extends far caudad and behind fuses 

 with the median funicular nucleus. The fibers of the first dorsal 

 spinal root terminate chiefly in this lateral nucleus. A slender fas- 

 cicle accompanies these root fibers and passes farther ventrally to 

 connect with the nucleus ambiguus (fig. 8, rxX/.^). These appear 

 to belong to the spinal accessory nerve, though their peripheral 

 destination is unknown. 



As we pass caudad from this level both the dorsal somatic com- 

 missure between the lateral funicular nuclei and the visceral com- 

 missural nucleus disappear, the place of the latter being taken by 

 the somatic commissural nucleus and the commissure between the 

 median funicular nuclei, which have meanwhile rapidly enlarged. 

 The spinal V nucleus is indistinguishable from the funicular 

 nucleus. The somatic commissural nucleus is only moderately 

 developed (figs. 9, 10), and in this region the somatic commissura 

 infima is represented by scattered fascicles of medullated fibers 

 between the funicular nuclei and formatio reticularis. The fun- 

 icular nucleus lies unusually far caudad and farther back passes 

 over into the dorsal cornu, which continues to be large far back 

 into the spinal cord, where it becomes enveloped by the large dorsal 

 funiculus. 



Anguilla, the common eel, is essentially the same as Conger, the 

 visceral system being relatively smaller. These fishes illustrate a 

 very high development of the somatic longitudinal conduction 

 paths of the somatic sensory centers of the medulla oblongata. 



The commissura infima of Prionotus I have elsewhere described 

 (1907a). In this species, as in the other gurnards, the visceral sen- 

 sory system is rather poorly developed, but the somatic sensory 

 systems, especially the spinal tactile centers, are very extensive. 

 The "accessory lobes" of the cephalic end of the spinal cord are 

 enlarged dorsal cornua and the first lobe includes also the spinal 

 V nucleus. The funicular nucleus is very greatly enlarged. The 

 visceral commissura infima and commissural nucleus are rather 

 small but of the typical teleostean type. The somatic commissura 



