UROGENITAL SYSTEM OF MYXINOIDS 79 



The work was done in the Zoological Laboratories of the Uni- 

 versity of Ilhnois under the guidance of Dr. J. S. Kingsley. I 

 wish to acknowledge my sense of obligation to Dr. Kingsley for 

 his kindly interest and helpful suggestions, always ^^dllingly 

 given. 



OBSERVATIONS 

 J. EXCRETORY SYSTEM 



The investigation of the excretory apparatus is based upon 

 Bdellostoma stouti, and the results will be presented by describ- 

 ing the organs of this animal and by interjecting, from time to 

 time, comparative notes regarding the same organs in the 

 American Myxine. Unless, therefore, it is specifically stated 

 otherwise, the content of the following discussion refers to 

 Bdellostoma stouti. 



Pronephros 



The right pronephros lies in the right pericardial cavity imme- 

 diately dorsal to the portal heart and along the dorso-lateral 

 surface of the alimentary canal, parallel to the dorsal aorta. In 

 figures 1 and 3, which illustrate the position of the right pro- 

 nephros of Bdellostoma and MjTcine, respectively, in the peri- 

 cardial cavity, the lateral wall of the cavity has been cut away, 

 but the edges of the pericardium which form the pericardo- 

 peritoneal foramen are shown. The pronephros lies along a 

 large diverticulum extending posteriorally from a vein which 

 is called by Jackson ('01) the anterior portal and by Cole ('14) 

 the right anterior cardinal vein. I have had no opportunity to 

 examine injected specimens, but from a study of serial sections 

 the writer agrees with Price ('10) that this vessel is merely a 

 diverticulum with no posterior outlet. In Myxine glutinosa, 

 however, Cole ('14) has shown that this vein extends posteriorly 

 after leaving the pronephros and enters the supra-intestinal 

 vein. In a single poorly injected specimen of the North- Ameri- 

 can Myxine the wTiter found a small twig extending posteriorly 

 from this vein toward the supra-intestinal vein and a larger 



