[352] 



ON THE 



NERVOUS SYSTEM AND SENSE ORGANS 

 OF AMIURUS. 



BY PROF. R. RAMSAY WRIGHT, TORONTO. 



[Bead before the Canadian Institute, January the 12th, 1SSU. ] 



In the course of the investigations, the results of which are de- 

 tailed in the following pages, some features in connection with the 

 nervous system and sense organs of Amiurus appeared to me of 

 special interest. These have been elaborated at the expense of other 

 points which would prove no doubt equally worthy of closer exami- 

 nation, but which did not at first sight appear so promising as fields 

 of enquiry. The treatment is consequently not monographical, 

 although for the sake of completeness a short account has been in- 

 serted of some structures which have not been subjected to special 

 study. 



Of the sense organs, the olfactory does not appear to be either 

 more or less developed than is usual in Teleosts. The eyes on the 

 other hand are extremely small, a condition which is compensated 

 for by the exquisite development of tactile sensibility on the head and 

 especially on the barblets. The latter serve to increase the range of 

 the tactile sense ; especially is this the case with those which are car- 

 ried on the ends of the modified superior maxillary bones, for their 

 muscular connections enable them to be swept freely at the sides of 

 the head. Also, the auditory organ and the sense organs lodged in 

 the canals of the lateral line and head are well developed, and the 

 former is connected with the air-bladder in such a manner as to indi- 

 cate functional relationships of the highest importance. 



The importance of these sense-organs is sufficiently indicated by the 

 large size of the nerves distributed to them, and the central connec- 

 tions of the latter naturally determine many peculiarities in the 

 architecture of the central nervous system. Considerable space is- 



