ON THE HEAD KIDNEY OP MYXINE. 353 



On the Head Kidney of Myxine. 



By 



J. W. Kirkaldy, 



Somerville Hall, Oxford. 



With Plate 23. 



In a former number of this Journal Professor Weldon has 

 given an account of the structure of the pronephros of 

 Bdellostoma (9)^ but, so far as I know, that of Myxine is 

 undescribed, excepting for some observations made by Professor 

 Wilhelm Miiller (8). Professor Weldon has very kindly 

 furnished me with some specimens of Myxine glutinosa, 

 in order that 1 might examine the head kidney. I should 

 like here to express my thanks to him for this kindness, 

 and also for advice and assistance given me throughout the 

 investigation, which was conducted in his research laboratory 

 in University College, London. 



The head kidneys of Myxine are situated towards the anterior 

 part of the body, a little behind the external gill-slit, and a 

 little in front of the fore-end of the mesonephron. Each is an 

 elongate organ, showing on the surface a much convoluted 

 tuft of tubules (fig. 1, p. t.), the pronepbric tubules of Miiller, 

 and projects into the pericardial cavity just beneath the heart, 

 being also connected with the anterior extremity of the post- 

 cardinal vein. I have been unable to trace any connection 

 between the pronephros and the segmental duct. 



Of the material upon which I have worked, some individuals 

 contained large ova, whilst others did not, and the pronephros 

 of an animal containing ova differs in many respects from that 



