228 



For this reasou and also because the terminal portion of the 

 nephridial duet takes rather an uuexpected course in the segments 

 where the nephridiopores are dorsally situated I feel justified in 

 publishing this short note. 



1 will first give the result of' an unbroken series of sections 

 through twenty-seven segments of the hinder portion of the body. 

 On the right side I find that the nephridiopores are situated just 

 above the second seta in segments (numbered according to their 

 order of succession in the series) 1, 5, 9, 10, 11, 13, 15, 17, 

 19, 20, 22, 24 and 27. 



On the left side they occupy this position in segments: 3, 5, 

 6, 7, 11, 13, 14, 20, 21, 22, 23, 24, 25, 27. 



Nephridiopores above the fourth seta , the majority being about 

 half way between this and the dorsal pore, are found on the 

 right in segments 2, 3, 4, 6, 7, 8, 12, 14, 16, 18, 21, 23, 25, 

 26 and on the left in segments 1, 2, 4, 8, 9, 10, 12, 15, 16, 

 17, 18, 19, 26. 



There appears thus to be no definite order of succession , 

 either on oue side, or on comparing both sides with each other. 



It is however worthy of remark , that of these 54 nephridio- 

 pores situated in 27 segments , there are 27 in the superior, 27 

 in the inferior position. 



Of those that occupy the superior position I find about one 

 fourth situated just above the fourth seta, whereas three fourths 

 are found about half way between this fourth seta and the 

 dorso-median pore. Positions intermediate between these two are 

 exceedingly rare. 



sup])lied in this deficiency had it been differently interpretated. What are there figiired 

 as dorsal pores (in addition to the median ones which open out between the segments) 

 «situated, not in the intervals between the rings, but on the sides of the rings thera- 

 '/Selves at a greater or less distance from the dorsal median line" are undoubtedly dorso- 

 lateral nephridiopores. It is moreover said about them that „they vary in their relative 

 position which is not subject to auy regularity" but neither Busk nor Ray Lankester 

 furnish us with an cxplanation as to their definite siguificance, Lankester mentioning 

 the nephridiopores as being situated ./uear the median ventral line" (1. c. p. 17) 



The number ot' openings as figured by Busk fairly corresponds to what is indicated 

 in the following table (p. 230), and as in my two specimens so in Busk's drawing 

 I find a somewhat larger number of (superior) nephridiopores in the right half of the body. 



