The Journal of 



Comparative Neurology and Psychology 



Volume XVII JULY, 1907 Number 4 



THE TACTILE CENTERS IN THE SPINAL CORD AND 



BRAIN OF THE SEA ROBIN, PRIONOTUS 



CAROLINUS L. 



BY 



C. JUDSON HERRICK. 



{Studies from the Neurological Laboratory of Denison University, No. XXI.) 



With Fifteen Figures. 



The nervous system ot the gurnards (notably the European 

 genus Trigla) has long been recognized as exhibiting points of 

 special interest from the standpoint of functional differentiation. 

 The brains of these fishes differ but little externally from the 

 usual teleostean type, but the cephalic end of the spinal cord 

 exhibits a series of segmentally arranged dorsal enlargements 

 ("accessory lobes," Ussow) which receive huge nerve roots from 

 the specially modified free rays of the pectoral fins. Since the 

 demonstration by Morrill ('05) that in the allied American 

 genus, Prionotus, the function of the free rays and their specially 

 modified nerves is purely tactile and that neither gustatory sensa- 

 tion nor specially modified end-buds of any description are found 

 upon them, the neurological interest of these fishes is enhanced. 

 For it now appears that these lobes are simply enlargements of 

 the dorsal cornua of the spinal cord and their associated fiber 

 tracts and that they therefore exhibit an extraordinary develop- 

 ment of the unspecialized somatic sensory system uncomplicated 

 by any other modifications. 



Through the kindness of Professor I. A. Field of Western 

 Maryland College I have received a number of brains, with a 

 portion of the spinal cord attached, of Prionotus carolinus from 

 which serial sections were cut for me in the transverse and hori- 

 zontal planes and stained by the method of Weigert by my 



