260 



forward under the opticus. In both fishes the nerve is said to 

 innervate certain of the cranial muscles, and those muscles, though 

 thus not homologous in their manner of innervation, are apparently 

 homologous in position and function, though the descriptions are not 

 quite clear as to this. Pollard (25) considers the ophthalmic nerves 

 of these two fishes as the homologues, not of the ramus ophthal- 

 micus, but of the "ramus premaxillaris" of his own descriptions 

 of Siluroids, a nerve that is said by him to be a branch of the 

 maxillaris trigemini; and he refers to the course of the ophthalmic 

 nerves in Bdellostoma and Myxine as proof positive of the proposition 

 that underlies all his work, that the course of nerves is of no great 

 importance. He never questions , and no author excepting myself 

 seems ever to have seriously questioned, the absolute accuracy of 

 Müller's and Fürbringer's statements. 



Having during the past year received several adult Bdellostoma 

 dombeyi, I determined to at once control Müller's statements regarding 

 the ophthalmic nerve of this fish ; and, as I fully expected, I found 

 at once that he had made certain errors and omissions of observ- 

 ation, radically important in this connection. This led me to trace 

 the apparent central origin, and the larger part of the peripheral 

 course of all the branches, both of the trigeminus and facialis nerves. 

 These and related observations, together with certain evident de- 

 ductions based upon them and relating to the cranial skeleton of the 

 fish, are what the present paper proposes to set forth. 



But one figure is added to the text, for reference to Müller's 

 several works, to Parker (22), and to the recent work by Ayers 

 and Jackson (5) will, in almost every instance, amply suffice. Because 

 of the more complete nomenclature, and more definite figures, I shall 

 employ, in my descriptions, the names given by Ayers and Jackson 

 to the several parts of the cranial skeleton; but certain of these 

 names are certainly wrongly applied, as will appear in the discussion 

 of the skull. In referring to the muscles I shall use the names given 

 by Fürbringer to the corresponding muscles in Myxine. I do not 

 describe the muscles because Ayers and Jackson announce that they 

 have a work already in press, relating to this subject. 



My specimens were sent me by my assistant, Mr. W. F. Allen, 

 who has collected them at Pacific Grove, California. Certain embryos 

 were also sent me by Mr. Allen, but as they are all more or less 

 imperfect, doubtless for the reasons so fully set forth by v. Kupffer (17), 

 I have made but little use of them in this study. The work on the 

 adult has been confined almost entirely to serial sections, though dis- 



