SarhdrHck verboten " 

 Uebersetzungsrecht vor h' halten. 



The Oral Cirri of Siluroids and the Origin of the 

 Head in Vertebrates. 



By 

 H. H. Pollard, Oweus College, Miinchester. 



With Plates 24—25 



Contents. 



Introduction. 



Technique. 



On the occurrence of oral cirri. 



Descriptive part: 



Models of Auchenaspis, Silurus, Trichotnycterus and Call- 

 ichthys. 



Sensory tentacular nerves of Auchenaspis, Trichotnycterus, 

 Callichthys and Myxine. 

 Comparative part : 



Nasal tentacle and nerve supply. 



Premaxillary tentacle and nerve supply. 



Maxillary and coronoid tentacles. 



Origin of the cranium. 



Labials and nerve supply. 



Mental tentacle and e.xtramental. 



Submandibular tentacle. 



The Meckelian cartilage. 



Other parts of the head. 

 Histologj' 



Reversion and larval forms. 

 Zoological position of Siluroids. 



Introduction. 



Nearly four years ago, I found in the cellar of the Anatomical 

 Buildings at Freiburg i./B. a number of Siluroids, which Prof. Wiedkrs- 

 HEi.M (»penhandedly placed at my disposal, and I then began my study 



