The Latero-Sensory Canals and Eelated Bones in Fishes. 473 



previous work [5, p. 172], the one to the third, aud the other to the 

 second and first groups together of infraorbital organs in Amia and 

 Scomber. These two lines in Chimaera also probably correspond to 

 the two suborbital lines in Batrachus; and the ventral one alone, if 

 Herrick's conclusion, already referred to, is correct, would then coi^re- 

 spond to the single line of Lophius, and hence probably to the single 

 line in CÜiaunax also. Two organs of the supraorbital canal are said 

 by Cole to be innervated by a branch that arises from the ramus 

 ophthalmicus profondus, but Burne [20] says that that branch of the 

 latter nerve that apparently supplies these organs receives anastomo- 

 sing branches from the ramus ophthalmicus facialis; the fibres of 

 these latter branches thus undoubtedly supplying the two sense organs. 

 That part of the supraorbital canal of Cole's descriptions that 

 is called the subrostral by Garman [39], corresponds markedly in 

 position to the nasal, median and prenasal canals together of Garman's 

 descriptions of selachians, but those canals of selachians belong to 

 the infraorbital and not to the supraorbital line. This correspondence 

 of these lines is strikingly evident in a comparison of Garman's 

 frontal views of Chimaera and Isurus, but the innervation in Chimaera, 

 as given by Cole, and that in selachians as given by Ewart and my- 

 self, shows that there is here only an imitative, though noteworthy 

 resemblance. The so-called nasal canal of Chimaera, it is to be 

 noted, has not at all the position of the nasal canal of selachians, 

 the latter canal lying oral to the nasal apertures, while in Chimaera 

 it lies postoral to them. The canals and apertures are thus not 

 homologously related to each other, but that the canals are, for this 

 reason, not homologous, I am not prepared to say. According to 

 R. G. Harrison [45] the "anlagen" of the latero-sensory lines, as they 

 develop from some central position, follow predetermined lines of 

 least resistance. If then the nasal apertures should for some reason 

 change their topographical position, the nasal canals might not be at 

 all affected. This same principle might, furthermore, explain the 

 peculiar course of the supraorbital groove of Chimera. Assume that 

 for some reason the suborbital line has been separated into two 

 somewhat parallel portions, as is actually the case, and that the 



