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On the AFFINITIES, INTER-RELATIONSHIPS, 
and SYSTEMATIC POSITION of the 
MARSIPOBRANCHII. 
By G: B. Hows; WES. f-7.5., 
ASSISTANT PROFESSOR OF ZOOLOGY, ROYAL COLLEGE OF SCIENCE, LONDON. 
With Plates VIII, IX and X. 
[Read November 18th, 1891.] 
I. The Lampreys (Petromyzontide) and Hags (Myz- 
inid@) have been classed together by Johannes Muller 
as the Cyclostomata,* by Prince Bonapartet as the 
Marstpobranchi, and by Huxleyt as the Myzichthyes. 
They have been defined by Gunther§ as animals ‘“‘ without 
real jaws,’ while Beard (following Dohrn, and having dis- 
covered in them the existence of vestigial calcified teeth) 
concludes|| that they ‘‘ must undoubtedly be added to the 
gnathostomatous vertebrata.” These citations, although 
by no means exhausting the alternative views current 
concerning their affinities, sufficiently testify to the exist- 
ence of conflicting authoritative opinions, and justify a 
further enquiry into the facts upon which these are based. 
Choice between them must needs depend upon what 
is understood by a “jaw” and a ‘“‘ gnathostomatous 
vertebrate,” respectively. 
* Abhandlg. d. Konig. Akad, Wiss. Berlin, 1834, p. 76 (=the classical 
‘ Myxinoiden ”’). 
+ Synopsis Vertebr. Systematis. Rome, 1837, p. 25. 
+ Proc. Zool. Soc. Lond., 1880, p. 660. 
§ Introd. to Study of Fishes, 1880, p. 691. 
| Spengel’s Zoolog. Jahrb, (Morph. Abth.) Bd. ITI, p- 747. 
