Herrick, Medulla Oblongata of Fishes. 413 



4. A fourth component is the descending secondary gustatory 

 tract from the facial lobe, which ends in the median and lateral 

 funicular nuclei arid also passes far downward into the spinal cord. 



5. A well defined bundle, marked x on Figs. 3 and 4, extends 

 cephalad into the oblongata beyond the funicular nuclei closely 

 accompanying the spinal V tract. This bundle can be distin- 

 guished in Ameiurus as far cephalad as the motor V and VII 

 nuclei. In Prionotus a similar bundle can be followed with ease 

 through the whole length of the oblongata to the cerebellum, which 

 it enters dorsally of the ascending secondary gustatory tract and 

 nucleus. Although I have not been able to follow this tract with 

 certainty into the cerebellum in Ameiurus, I feel sure that its course 

 is the same as that of the similar tract of Prionotus. My prepara- 

 tions do not enable me to say whether it is an ascending or a de- 

 scending tract. I presume that it is ascending, and have accord- 

 ingly provisionally designated it, tractus spino-cerebellaris. In 

 Ameiurus a large proportion of its fibers seem to end in the facial 

 region of the oblongata. 



Internally of the fasciculus lateralis is a compact bundle of 

 heavily medullated fibers which probably arise in the dorsal cornu 

 and immediately cross in the ventral commissure as internal 

 arcuate fibers. This tract, which I term the tractus-spino-tectalisy 

 is joined by the similar fibers of the tractus bulbo-tectalis in the 

 medulla oblongata and both terminate together in the colliculus 

 of the mesencephalon. In its upper course this tract was termed 

 the lateral longitudinal bundle by Stieda and Mayser and lem- 

 niscus in my former paper (Herrick, '05, p. 386). The tract as 

 a whole is undoubtedly homologous in a general way with the lat- 

 eral lemniscus of mammals. Unfortunately an entirely different 

 tract, the tractus tecto-bulbaris et spinalis, has been called lem- 

 niscus by several of the leading students of fish brains. 



Passing cephalad, as we approach the end of the spinal cord, in 

 Ameiurus the cornu dorsalis rapidly expands and becomes clearly 

 differentiated into two parts which are very distinct in Weigert 

 preparations (Fig. 2). Meantime the formatio reticularis has also 

 enlarged, especially dorso-laterally of the canalis centralis. The 

 deeper one of the gray derivatives of the dorsal cornu is intimately 

 connected by means of medullated and unmedullated fibers with 

 this formatio reticularis. It is the nucleus funiculi, or to distinguish 

 it from the lateral funicular nucleus to be described below, I shall 



