14 ART. 11. — A. 1ZUKA : OBSERVATIONS ON TUE 



the anteriormost para podium to about the 20th and then begin 

 to become smaller posteriorly until in about the 140th they 

 become united together, finally to disappear altogether some dis- 

 tance still farther posteriorly. 



The blades of the falcate bristles, which constitute the 

 lower-anterior bunch of the ventral ramus, grow stronger from 

 the anteriormost parapodium to about the 20th, in which the 

 maximum development is reached (being about 1 1 times the length 

 of the 30th parapodium). Then they become smaller again to 

 about the 25th or the 26th, after which they remain of nearly 

 the same size until the posterior region of the body is reached. 



The length of the setose bristles of the lower-posterior bunch 

 is subject to much variation. It continues to increase from the 

 front region posteriorly until the maximum length (about 1 J times 

 that in the 30th parapodium) is reached in about the 60th 

 parapodium, and then the same length is maintained to about 

 the 100th or so, whence posteriorly it again diminishes. The 

 variation in length of the bristles forming the upper-posterior 

 bunch generally coincides with that of the bristles of the bunch 

 just described. 



In the upper-anterior bunch, the bristles vary not only in 

 size but also in form. In the first 23-24 parapodia, the bunch 

 consists exclusively of falcate bristles, just like those in the 

 lower-anterior bunch. From about the 20th parapodium, their 

 number in each bunch begins to decrease, while the shorter setose 

 bristles in the bunch constantly increase in number, until in the 

 28th-30th the latter entirely replace the falcate variety. The 

 setose bristles as they occur together with the falcate in the same 

 bunch in the 20th-26th parapodia are slightly longer than the 

 latter. Posteriorly they continue to increase in length to about 



