INTRODUCTION. 



OBJECTS. 



A list of the families of fishes having long been urgently needed for the 

 re-arrangement of the extensive collections of those animals in the Smith- 

 sonian Institution, the following has been drawn up. The author has long 

 delayed its publication in order to continue his investigations and extend 

 them into some more of the many doubtful questions that still involve 

 ichthyology, but as such considerations would cause an indefinite post- 

 ponement of publication, and as the list itself is desirable as a starting- 

 point for renewed investigation, and is, of course, more available in a 

 printed form than in manuscript, it is now printed ; being printed, its 

 publication has been deemed advisable as it may supply to others the 

 want that has been experienced by the Smithsonian Institution. That 

 it will stand the test of time as to many details is not to be expected. 



STATUS OF ICHTHYOLOGY. 



Studies in ichthyology have, for the most part, been directed to the ex- 

 ternal organization, and the characters of all but the highest groups have 

 been chiefly derived from features visible from the exterior, and modifica- 

 tions of single organs whose co-ordinations with other modifications, and 

 consequently taxonomic values, have not been veriGed. If a system 

 among fishes thus established has proved to be more true to nature than 

 analogous ones would be among the mammals, birds, or reptiles, it is 

 because so many of the elements of the skeleton, such as the jaws, oper- 

 cular bones, suborbitals, scapulars, branchiostegal bones, and rays are 

 more or less exposed to view, and the modifications more or less noted, or, 

 when concealed, the contrast taken cognizance of. A classification based 

 on superficial features in the fishes is thus, to a considerable degree, the 

 expression of skeletal modifications, which are themselves the co-ordinates, 

 as experience has shown, of others. For though the characters derived there- 



(vii) 



