Arwidsson — On some Irish MaMnvicJae. 



211 



setae on either side of the hindmost segment, which is usually free from setae 

 (fig. 16). On three individuals capillary setae are developed on the left-hand 

 side, and on one on the right-hand side ; one of the first set comes from 

 Blacksod Bay, while all the rest are from Howth. 



The cup-shaped section at the hindmost extremity is rather short, and 

 but little longer on the ventral than on the dorsal side (fig. 16). The 

 majority, at least, of the anal cirri are like fingers, and are of approximately 

 the same length ; but they appear to be somewhat shorter towards the dorsal 

 side. Besides these, however, there occur, except in the case of the largest 

 individuals (fig. 18), one or more smaller cirri between the larger ones. Of 

 these smaller cirri those are particularly noticeable which are almost always 

 found developed upon both sides or upon only one side of the ventral nerve- 

 cord ; often these are merely indicated by a little fold ; in the individual 

 represented in fig. 18, even these are absent. The numbers of cirri found in 

 all the individuals investigated are set forth in the following table : — 



Nos. 1-8 (all small ones) are from Blacksod Bay, the others are from Howth. 



No. 



Number of cirri, with the exception of the 

 smaller ones near the ventral nerve-curd. 



Number of cirri adjacent to 

 the ventral nerve-cord. 



(«) Medium size. 



(b) Distinctly small ones are 







among- tlie larger. 





1. 



IS 



1 



2 



0. 



20 



tiaees of 1 



traces 'of 2 



3. 



16 



traces of 1 



2 (very small) 



4. 



18 



2 



traces of 1 



5. 



17 



1 



traces of 2 



.6. 



16' 



— 



1 



7. 



17' 



— 



2 (very small) 



8. 



18' 



— 



traces of 1 



9. 



19 



— 



2 distinct unes 



10. 



18 



2 of medium length 



1 of medium length to the 

 left 



11. 



16 



1 (small) 



2 (one being quite short) 



12. 



19 



— 



2 rather long ones 



13. 



e. 19 



— 



1 



U. 



17 



— 



— 



lf>. 



IS 



— 



1 (short) 



16. 



17 



2 (small) 



1 (short) 



In these three individuals, in particular, the highest cirri are =ni;ill on the whole. 



[2 G 2] 



