156 BIOLOGICAL LECTURES. 



Bdellostoma polytrema (Girard), 1854. 

 " " (Giinther), 1870. 



" (Putnam), 1874. 



" Stoutii (Lockington), 1878. 



Polistotrema dombeyi (Gill), iSSi. 



(Jordan, Gilbert), 1882. 

 Bdellostoma forsteri. / 

 " cirrhatus. > 



" hexatrema. 



" heterotrema. 



heptatrema. 



I shaU, for my own convenience, hereafter use the numerical 

 method of designating the varieties ; and, unless sufficient 

 reasons be brought against this style of name, I would urge 

 its adoption on the ground of convenience, to go no further. 



Bdellostoma dombeyi, 6 gills. 



" " 6-7. ) Indicating the sides of the body upon 



" " 7-6. \ which the respective numbers occur. 



PHYSIOLOGICAL. 



From previous experience it seemed to me very desirable 

 that physiological experiments should be tried upon the ear 

 of some vertebrate with the simplest existing type, and, if 

 possible, upon an animal which lacked fins, /. c., paired 

 appendages, which in all fishes are specially used in main- 

 taining the equilibrium of the body. I felt that by securing 

 these conditions, we should be able to get much cleaner 

 responses or, in any case, safer results from operations on 

 the ear, for the presence of the paired fins especially the 

 pectoral -fins complicates the reaction to ear operations by 

 introducing into observable phenomena mechanical factors 

 whose influences have not been carefully enough studied and 



