444 T. H. MORGAN. 



A few of the more obvious relations that one finds in these 

 tables may be pointed out. In some cases exceptions to the 

 statements made above are found. At a in the third record^ 

 last (fifth) column, we see that a half-colour band is present on 

 one side, but not on the other. And again this is seen at a 

 in the third record, fourth column. 



In the third record, first column, we find in one region many 

 irregularities present, although taken altogether the same 

 number of half-rings are present on the right and left sides. 



In the third record each arm was found to have a new distal 

 end that had regenerated. In this part every other segment 

 was coloured. Whether this was a permanent or only a tem- 

 porary coloration I cannot say. 



It would be interesting to find out whether in the same in- 

 dividual similar variations showed a tendency to appear on 

 the different arms. Even the limited data of the three tables 

 give a slight amount of evidence in favour of such a view. 



The regular arrangement of the colour-bands on every fourth 

 segment finds an interesting parallel in certain Annelids, where 

 the coloured rings bear a more or less definite relation to the 

 metameres of the body. 



Andrews (1) makes the following statement in regard to the 

 arrangement of coloured bands in the polychsetous Annelid 

 Procersea tardigrada, which belongs to the family Syl- 

 lidae: — "The female has a dark dorsal transverse band upon 

 Somites 3, 6, 8, 9, 13, 17, 21, 25, 27, 29, 32, 35, 38, 42, 46, 

 49, 51, 53, 56, 57, 70, 71, 74, 77. . . . The non-sexual form 

 has pigmented bands like those of the female, but arranged 

 according to a definite law or general rule, to which the bands 

 in the female conform also ; bearing in mind that the female is 

 formed as a cut-off part of the non-sexual stage, separating 

 almost always just posterior to the thirteenth somite, and 

 hence having thirteen less somites than that stage. In 110 

 individuals carefully studied, only tiiree had the bud formed 

 just posterior to the fourteenth somite ; seventy-nine had an 

 evident bud just posterior to thirteenth somite. 



" Having tabulated the arrangement of the coloured bands in 



