hall: mesonephkos and mullerian duct in amphibia. 



Oi 



Explanation of Diagbau 1. 



Mesonephric units of Amblystoma plotted according to position in the somite. Individual 

 larvae denoted by the letters A to U, with their lengths in millimetres immediate!}' be- 

 low. Somites 9 to 20 are numbered in the extreme right-hand and left-hand columns. 

 The units are represented by solid circles or ovals, — rings indicating indistinct funda- 

 ments, whose number is uncertain. Circles numbered 2, 3, 4, and 5 (L- U) represent 

 the most anterior of the secondary, tertiary, etc. units. The wavy lines indicate the ex- 

 tent of the germ-cell mass. Crosses (in individuals K-0) show the position of the most 

 posterior of the functional units. The position of the opening of the Wolffian duct into 

 the cloaca is shown at the bottom of the diagram (somite 20). 



Table 1. 



Showing the number of units to each somite. The individual larvae are designated by the 

 letters Bio U ; the somites, by the numbers (9 to 20) in the first column. 



