MR. E. R. LANKESTER ON SOME LOWER ANNELIDS. 64 



large ciliated prostomium and the mouth projecting outwards; the alimentary tract ifl 

 ciliated throughout, but the outside of the body is not, excepting the prostomium. A 

 few stiff hairs or "palpocils" project from the integument, such as are well known in 



Turbellaria, in Nematodes, and iu Nais and Chmtogastcr, and which are seen also 



young 



the adult JEolosoma. 



The specimens of JEolosoma disappeared from the water that contained them, and I 



o 



et no more. As it is unlikely that I shall succeed in so doing yet a while, I 



not think it necessary to keep back the above notes, though incomplete. 



Ehrenberg describes three species of JEolosoma. I suppose that my species is his 

 JE. quaternarium. 



IV. Relations of Cluetogaster and iEolosoma to some other lore forms of Annelida 



JEolosoma and Clicetogaster are both associated by D'Udekem and J. V. Cams with 

 Nais, in the lowest of four families into which the Oli^ochseta are by them divided; at 

 the same time no mention is made of two other low forms with which they ought to be 

 associated. JEolosoma, in its double series of bristle-bundles, in its large prostomium, 

 in the coarse ciliation of its alimentary tract and lip, and in its larger number of seg- 

 ments and greater differentiation of its tissues, certainly presents characters which bring 

 it nearer to Nais and the Lumbricoid Oligochetes than any presented by Cha'togaxtcr. 

 But it also approaches Clicetogaster in the paucity of its segments, the red vesicles of 

 its integument, and the comparative lowness of its organization. JEolosoma is, it 

 appears to me, much nearer to Nais than to Chwtogaster. Are there any forms which 



bridge over the gap ? 



Oscar Schmidt, in the « Sitzungsber. Akad. TTien, vol. xxiii., describes very briefly a 

 Tarthenope serrata, which seems to have been quite overlooked since. Claparede, in his 

 ' Beobacht. iiber Anat. u. Entwickelung der wirbellosen Thiere,' describes briefly and 

 figures the same worm under the name Ctenodrilus pardalis. He does not allude to 

 Schmidt's species ; but undoubtedly his is of the same genus. Claparede's figure is the 

 most complete ; he remarks that he considers the worm to be a marine Oligochete, but 

 has only met with it once, and he gives no anatomical details. Neither Schmidt nor 

 Claparede says anything as to the relations of this worm to the Oligochaeta. 1 1 is a minute 

 creature, of the same size as the Ch. limnaii, or even less, has a short worm-like figure, 

 hut no definite segmentation, whilst its integument appears not to be tough. Its seta? 

 are pectinated at the apex, or, rather, notched with five teeth ; they are arranged in 

 bundles of five placed in pairs on the ventral surface; Claparede figures five such 

 Pairs. The prostomium is very large, and ciliated like that of .Eolosomc, whilst the 

 integument is spotted with brownish clear vesicles arranged in clusters, whence the 

 name pardalis. This form very obviously connects Clicetogaster and jEolosoma, havm 

 the ciliated prostomium of the one, and the uncinate bristles, in a ventral series, of the 

 other. Both Schmidt and Claparede found it in the Mediterranean. The ciliated broad 

 Prostomium of JEolosoma is strangely like that of , some Turbellaria, as for instance 

 Mcrostomum lineare, in which the mouth and prostomium have almost exactly the same 



4 u 2 



vr 



