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by Cole he must have intended that they should be taken literally, 

 and the word "should" indicates that the expression is intended to be 

 the statement of a principle rather than one of facts. The facts are 

 rather against the statement, taken literally, as Cole's extensive reading 

 must certainly have shown him. Cole's definitions of the lateral canals 

 can not, however, always be taken literally, as, for instance, the general 

 classification of the lateral canals of fishes and Amphibia, given on 

 p. 635 of his work on Chimaera. 



To the terms main canal, or main lateral canal, as since proposed 

 and used by certain writers, in place of infraorbital or main infra- 

 orbital 'canal there are certain objections. Each canal of the entire 

 system is a main canal when its peripheral branches are being con- 

 sidered, and must, in detailed descriptions, be so referred to, and hence 

 lacks precision. To the term main lateral canal there is the serious 

 objection that the organs of the infraorbital line of the head and those 

 of that lateral line of the body that form a direct posterior continuation 

 of the infraorbital line, arise, in Necturus, according to Platt (No. 18, 

 p. 541) , in connection with the so-called epibranchial ectodermal 

 thickenings of that animal ; the supraorbital Hne of the head, the ear, 

 and the dorsal body line arising in connection with the so-called lateral 

 or dorso-lateral thickenings. If this should be found to be also true of 

 fishes, the lines on which certain changes in existing nomenclature could 

 and should be made are sufficiently evident. 



The use of the names of the nerves to designate the canals they 

 innervate is strongly advocated by Ewart (No. 9), and I am often said 

 to have used and approved of this method. This is not an exact state- 

 ment of my practice. I used the names of the nerves, and still do, to 

 designate those particular parts, of the several canals that they innervate, 

 the names of the canals themselves, however, being based on purely topo- 

 graphical considerations. The nerves are certainly of primary value in 

 identifying and comparing the several canals, but they are not, alone, in 

 my opinion, a good and sufficient basis for a system of nomenclature. 

 This I have already stated in a work which is now in press, but which 

 will probably not be published until after this communication has appeared. 

 The sections of canal innervated by certain nerves in different fishes 

 vary greatly in extent, and sometimes even in position. A branch of 

 the buccalis facialis in Scomber, for example, innervates one organ in 

 the supraorbital canal of that fish 1 ); and the profundus trigemini, in 



1) The innervation of this organ, in Scomber, by a branch of the 

 buccalis seems to me to indicate that the nasal bone of Scomber is 

 the equivalent of the nasal of Amia plus either the antorbital bone of 

 that fish, or plus one half of the ethmoid. That branch of Gadus that is 

 said by Cole (No. 6, p. 158) to innervate a pit organ opposite the anterior 

 extremity of sense organ 1 supraorbital, may be the homologue of this 

 branch in Scomber. The course of the nerve in Gadus seems to indi- 

 cate that the pit organ it innervates belongs to a homologue of the 

 ethmoid line of Amia and not to the antorbital one, organ 1 infraorbital 

 being perhaps the homologue of an antorbital organ in Amia. The upper 



