90 MENSCH. [VOL. I. 



^ Seg. 25 26 29 39 40 41 45 48 

 54996423 



Seg. 19 21 24 52 58 



) Ind. i i 2 2 i 



> 



From this it will be noted that the position of the chain 

 occurs most frequently on some segment in Table A, varying 

 between segments 30 and 38, with a decided preponderance in 

 favor of segments 34, 32, and 30, respectively. In other words, 

 the greatest number of individuals have parent stocks of medium 

 length, with from 30 to 38 segments; and the position of the 

 chain on parent stocks of fewer or more numerous segments 

 than this range occurs less frequently as the number of seg- 

 ments becomes less or greater. 



Within the range in which the chain has been found to occur 

 most frequently, it will also be noticed that several segments 

 (3 1 - 33> 36) bear the chain much less often than others, so that 

 the chain-bearing phenomenon would appear to be confined 

 more particularly to certain ones of the segments in this range 

 (30, 32, 34, 37, 38). 



In observing the sex of the individuals tabulated, it was noted 

 that by far the greater majority of the specimens with the chain 

 attached to the thirtieth segment or anterior thereto bore female 

 stolons, while those with a great number of segments invariably 

 bore male stolons. In this lot of specimens examined no indi- 

 viduals with female stolons were found with a parent stock of 

 more than 41 segments, while those of 19, 21, and 24 segments 

 all bore female stolons. On the other hand, those of 45 and 

 more segments all bore male chains. Bearing in mind that the 

 first stolon of the series in the chain is formed by the separa- 

 tion of a number of segments from the posterior part of the 

 parent stock, this condition might possibly be due to the fact 

 that the female stolons always consist of a far greater number 

 of segments than do the male, and hence in the process of form- 

 ing the first stolon leave a more reduced parent stock ; while 

 in the process of forming the first male stolon fewer segments 

 would be required, and hence a longer parent stock left back. 



In P. ornata and P. tardigrada variations in the position of 



