1888.] WORM OF THE GENUS jEOLOSOMA. 21.0 



^. variegatum. Very frequently the epidermic cells cont.iined masses 

 of a yellow substance (Plate Xlf. fig. 8) which was not blackened bv 

 osmic acid, and which may, perhaps, be an excretory product of the 

 same nature as that which occurs in the cells of the peritoneum which 

 clothe the dorsal blood-vessel and the gut. These yellow masses 

 appeared to be most frequent upon the prostomium. Vejdovsky has 

 suggested ' that Leydig's jE. niveum may be identical with his 

 yE'. varieyatuui. The former species, however, has colourless oil- 

 globules ; but, as Leydig - pointed out, d'Udekem ^ has stated that 

 in ^. quaternarium the red oil-drops are recognizable in the 

 embryo, and Maggi's figures ^ of a very closely allied, if not identi- 

 cal, species show the same thing. Still jE. variegatum is so far like 

 ^. niveum in that it possesses colourless in addition to coloured oil- 

 globules, and it agrees in other particulars to be referred to presently. 

 In the species described in the present paper I also found colour- 

 less oil-bodies. 



The anterior margin of the prostomium is furnished with delicate 

 chitinous processes as in ^. variegatum ; and the under surface (Plate 

 XII. fii;. 2) of the ])rostoniium is ciliated as in that and other species. 



The number of setse in the bundles of ^E. variegatum is sated to 

 vary*, but the approximate number per bundle tabulated in Vejdov- 

 sky's memoir upon that worm is less than in the present Sf)ecies. 

 My species may differ as to the number of setse per bundle ; except 

 in the last few segments the number ranged from 4-0. Their shape 

 is perfectly similar to that of the setse in ^. variegatum. 



The accompanying drawing (Plate XII. fig. 3) shows the two seta- 

 bundles of one side of the body highly magnified ; each bundle is 

 implanted in a cellular sac which is plainly continuous vvitli the epi- 

 dermis, and is no doubt derived from it ; the sac is made up of 8-10 

 nucleated cells ; it is attached to the body-wall bv numerous 

 unicellular muscular fibres, each with a single nucleus at about the 

 middle of its length. The two seta-bundles are attached to each other 

 by a flat band of muscular tissue {sm), which is wider at its attached 

 extremities than in the middle ; this muscular band is longitudmally 

 striate, and is of a totally different appearance from the unicellular 

 muscular fibres above mentioned. 



I recognized the nerve-ganglion in the prostomium and the 

 ciliated pits, which lie on either side in the furrow which separates 

 the prostomium from the peristomial segment. The ciliation of the 

 prostomium extends as far as the ciliated pit. 



The alimentary tract shows but little difference from that of 

 other species ; observation of the hving worm as well as of trans- 

 verse sections (fig. ti) show that in my species the whole of the 

 intestine is ciliated. 



The vascular system calls for no comment ; the contained blood 



' System u. Morph. &c. p. llo, footnote. 



- MuUer's Arch. 18(55. ^ Bull. Acad. Bel". lS(il. 



; Soc. Ital. Sci. Nat. ISO."). 



' I am iiulobti-d to I'rof. Vejdovsky fur a German fr,iii.-,liaiuii ol' a pari of liis 

 meiiioir iijum Ai. varirg-ilum, which is in Bohemian. 



