Reprinted from the 'Quarttrly Journal of Microscopical Science,' July, 1893.] 



The Structure of the Pharyngeal Bars of 

 Amphioxus. 



By 



W. Blaxland Beiiliam, D.Sc.Loiicl., lion. M.A.Oxou., 



Aldrichian Demonstrator of Comparative Anatomy in the University of 



Oxford. 



With Plates 6 and 7. 



IT may be thought that the structure of the pharyngeal bars 

 of Amphioxus is sufficiently known, after the description 

 by Lankester, and more recently by Spengel; but there 

 still remains a certain amount of doubt as to some points in 

 the structure of the tongue or secondary bar, although recent 

 authors are in agreement as to the general structure of the 

 primary bar. It is to the tongue bar, therefore, that I have 

 more particularly directed my attention. 



Spengel contradicted Professor Lankester on several points, 

 both with regard to matters of observation, and more espe- 

 cially with regard to certain interpretations, in a very dog- 

 matic and, indeed, discourteous manner. I was surprised to 

 find that Professor Spengel himself is by no means correct 

 in sundry matters of mere observation. 



It will be remembered that Lankester, in addition to his 

 account of the structure of the gill bars which was, like his 

 figures, in great advance of the work of previous writers on 

 the subject made certain statements with regard to the spaces 

 within these bars; he attempted to distinguish, not only in the 



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