220 Proceedings of the Royal Irish Academy. 



setigerous segments, and of posterior achaetous segments : and thi-ee other 

 individuals investigated exhibit the same structure of the hind part as the 

 first-named. 



Kephridia are found in the seventh to the ninth setigerous segments, 

 of. fig. 3, which show the orifices on the ninth setigerous segment, whereas on 

 the other segments these do not here appear, but there can be seen beneath 

 the uncini a little field free from glands, which suiTounds each orifice. The 

 number of the nephridia has been determined by dissection. 



E]iid4:rmal Glands. — The cephalic plate (fig. 5) possesses distinct glands, 

 which are strongest on the anterior point and on the outer ends of the nuchal 

 organs. The anterior region is thinly covered with glands as far as somewhat 

 behind the parapodia of the first setigerous segment (figs. 1, 2, 5). The ventral 

 nerve-cord, however, imder the parapodia of the same segment is free (fig. 1). 

 Towards the rear there are, on the whole, onlj- some very few glands on the 

 sides at about the middle of the segment (fig. 2). The second to the seventh 

 setigerous segments, but the second to the fourth in particular, possess a free 

 edge anteriorly : the second setigerous segment has, in front of the parapodia, 

 a band of spai-se but large glands (figs. 1 and 2). Behind these there is a 

 number of very scattered glands straight behind the parapodia, some on the 

 ventral side and very few on the dorsal side anteriorly. The hindmost part 

 of the segment is free, or, in the larger individuals, it has glands to a faint 

 and scanty extent all tlirough ; the same is the case with the preceding 

 segment. The third setigerous segment, like the preceding one, has sparse 

 glands in front of the parapodia, but also over nearly the whole segment 

 (fig. 2), most thickly (in the smaller specimens) in a streak straight behind 

 the seta. The fourth to the seventh setigerous segments have — with the 

 exception of the free interior edges just mentioned, which moreover diminish 

 backwards — close-packed glands in front of the parapodia. On the fom-th 

 setigerous segment, moreover, these extend almost as far behind the parapodia 

 as to the front of them, but with some indication of a break on the dorsal side 

 behind the parapodia ; on the two following segments the glandular band 

 diminishes behind the parapodia, so that, especially on the last segment, it 

 scarcely surroands the parapodia. and at the same time the break mentioned 

 on the dorsal side becomes more distinct. On the venb-al nerve -cord, 

 however, there remains a number of glands, even fui'ther back ; and on the 

 sixth setigerous segment these join a faintly marked glandular ring round the 

 hinder part of the segment (fig. 2). On the hindmost parts of the fifth to the 

 seventh setigerous segments there are also, especially on the upper side, a 

 number of very thinly distributed glands. The seventh setigerous segment is 

 thickly studded with glands in front of the parapodia, with the exception, 



