82 



JESSE LE ROY CONEL 



It was observed that the right pronephros is usually slightly 

 larger than the left. In none of the specimens was a pronephros 

 found even one-half as large as those of Bdellostoma forsteri, as 

 reported by Weldon ('84), namely 20 to 25 by 5 to 7 mm. There 

 is no correlation between the size of the pronephros and the 

 length of the animal in Bdellostoma. Weldon does not give the 

 length of the animals examined by him, hence we do not know 

 whether the great difference in the sizes of the pronephroi of 

 Bdellostoma stouti and Bdellostoma forsteri may be explained 

 by a difference in the length of the two animals. The adult 

 Bdellostoma used in the present investigation range from 33 to 

 42 cm. long, averaging 38 cm. The pronephroi represented by 

 the above table are all from adult animals. 



The writer has been able to find only one statement re- 

 garding the size or shape of the pronephros in the adult Euro- 

 pean Myxine. W. Muller (75) mentions that they are 'lang- 

 lich,' 3 to 4 mm. long. Following is a table of dimensions of a 

 few pronephroi of the North-American Myxine: 



As is indicated by the above tables, the pronephroi of Myxine 

 are considerably larger than those of Bdellostoma. This is to 

 be expected from the great difference in the size of the adult ani- 



