Herrick, Tactile Centers of Prionotus. 317 



smaller and more lightly stained in Weigert preparations. This 

 tract can be clearly followed between the granular layer of the 

 body of the cerebellum dorsally of the superior secondary gusta- 

 tory nucleus (Fig. 15) and the spinal cord in the funicular nucleus 

 region. It retains its individuality perfectly as far, back as the 

 vagal lobe (Figs. 13 and 14); but in this region its outlines become 

 somewhat confused with those of the spinal V tract and other 

 elements of the dorso-lateral fasciculus. It can, however, be 

 separately distinguished, though its outlines are not clearly defined, 

 as far as the funicular nucleus (Figs. 11 and 12). I have no 

 doubt that it extends far back in the spinal cord in the fasciculus 

 dorso-lateralis below the accessory lobes, as figured by Edinger 

 ('96, p. 61, Fig. 30) for Trigla, though I am not able to follow its 

 fibers separately. Whether the direction of conduction is ascend- 

 ing or descending, I am not able to state. In other fishes where 

 I have found a spinal cerebellar tract it lies farther laterally and 

 ventrally in the oblongata. Except in Ameiurus, where I have 

 described it ('06, p. 413) under the name tr. spino-cerebelbris. 

 I am unable to account for its association with the spinal V tract 

 in Prionotus, noj^ even to assert positively its homology with the 

 more lateral tract of other fishes. 



CONCLUSION. 



The six "accessory lobes" or dorsal swellings of the cephalic 

 end of the spinal cord of Prionotus are simple enlargements of 

 the dorsal cornu evoked by the highly differentiated tactile organs 

 on the free finger-like rays of the pectoral fins. The first spinal 

 nerve is but little enlarged, but the dorsal roots of the second and 

 third are greatly so and give rise to the second to sixth accessory 

 lobes. 



The first lobe receives the first spinal nerve, very large spinal V 

 and spinal X tactile roots and secondary fibers of the fasciculus pro- 

 prius type from the accessory lobes farther caudad. The second 

 spinal nerve terminates in the second and third lobes, which are 

 broadly connected by short secondary tracts in the fasciculus 

 lateralis. The third spinal nerve terminates in the fourth, fifth 

 and sixth lobes, which are closely bound together by massive 

 short secondary tracts, as are the second and third. But between 

 the third and fourth lobes these short tracts (fasciculi proprii) are 



