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II[ A Monograph on the general Morphology of the Myxinoid Fishes, based on 



a study of Myxine. Part V. The Anatomy of the Gut and its Appendages. 

 By F. J. Cole, D.Sc. Oxon., Professor of Zoology, University College, Reading. 

 Communicated by Professor W. A. Herdman. F.R.S. (With Four Plates.) 



(MS. received October 5, 1912. Read December 16, 1912. Issued separately June 9, 1913.) 



CONTENTS. 



PAGE 



A. Habits 294 



B. Nasal Aperture and Mouth .... 295 



C. Body Cavity 296 



D. Respiratory Organs 298 



1. Structure of the Gills and Gill Ducts . 298 



2. Variations in the Branchial Organs . 303 



E. The Mucous Surfaces 304 



F. Histology and Divisions of the Gut . . . 308 



G. Liver and Biliary App>aratus — 



1. Superficial Anatomy . . . .317 



2. General Anatomy of the Liver 



3. Bio-chemistry of the Liver 



4. Histology of Gall Bladder 



5. Histology of Hepatic Ducts . 



6. Histology of Bile Duct . 



PAGE 



320 

 324 

 326 

 327 



328 



7. "Pancreas" 329 



H. Thyroid Gland 332 



J. Cloaca 335 



K. Literature ....... 338 



L. Explanation of Plates 341 



The first four parts of this work, on the skeleton, muscles, and vascular system, 

 were published in the Transactions of the Society in 1905, 1907, 1909, and 1912. 



The present section does not include the teeth, which, belonging properly to the 

 skin, will be described when the skin and its appendages are dealt with. It will be 

 noticed from time to time that I have to record striking differences from results 

 obtained by other authors. Such differences must, of course, be recorded ; but in 

 recording them it must not be understood, unless the contrary is expressly stated, that 

 the observations under discussion are necessarily inaccurate. One cannot investigate 

 Myxinoid anatomy without frequently coming up against somewhat astonishing varia- 

 tions, and 1 have long been convinced that there must be races or colonies of Myxine 

 which have not been distinguished specifically, but which, nevertheless, possess 

 anatomical features in common. To give one instance out of many. Mr R. H. Burne 

 has described in detail an anal slime gland in Myxine. In my sections of examples up 

 to 25 cm. there is no trace of this structure. On examining Mr Burne's sections I 

 find that the dorsal chamber of the cloaca has been converted into what anyone would 

 interpret as a slime gland, similar to the series at the side of the body developed in 

 connection with the skin. Mr Burne, therefore, is both right and wrong at the same 

 time, but no one with the material at his disposal could have deduced what the 

 supposed anal slime sac really was. 



I must express my indebtedness to Professor A. Meek and his assistant, Mr B. 

 Storrow, for their very successful efforts to obtain living specimens of Myxine, and for 

 the hospitality of the excellent marine laboratory at Cullercoats. The experiments on the 

 bio-chemistry of the liver were carried out by my museum assistant, Mr A. H. Malpas. 



TRANS. ROY. SOC. EDIN., VOL. XLIX. PART IL (NO. 3). 38 



