266 Transactions of the Society. 



ditches with a bottom of fine mud, in which the worm constructs an 

 erect cylindrical tube for its protection. The assumption is that 

 there was one species of TuUfex, just as there was one Lumhricus, 

 and here our trouble begins. Every observer for the last fifty years, 

 at home and abroad, has both been baffled himself, and lielped to 

 baffle others, because we have never yet obtained a clear definition 

 of " tubifex." It is assumed that the Lumhricus tuhifex of Miiller, 

 the Tuhifex rivulorum of the books, and a number of otlier worms, 

 all refer to one and the same species. A worm was found in the 

 mud, described, and named Tuhifex. Then another writer found a 

 worm and described it, but again called it Tuhifex ; and, when half 

 a dozen or more different worms had been so described, the question 

 was how to find a clear set of species-characters which would com- 

 bine all that the various writers had observed. Thus it resulted 

 that Tuhifex was said sometimes to possess only forked setffi, at 

 other times capillary setse as well, while it might even possess 

 pectinate at times in addition. One writer said no penis-sheath was 

 present, another that it was ; then one described the sheath as 

 resembling a vase, and another as being several times longer than 

 broad : never dreaming that all the time different species, and even 

 different genera, had been under observation. Thus the true 

 Tuhifex in time became a chimera. 



Lankester was one of the first English authors of note to take 

 up the subject. In 1871 he published an article in the Ann. and 

 Mag. Nat. Hist., in which he dealt with a form of Tubificid known 

 as Psammoryctes, found in brackish water at Barking. In 1885 

 appeared Eiseu's valuable Oligoch^tological Eesearches, and a con- 

 siderable addition was thereby made to our knoM^ledge of the family. 

 But it was not till 1891 that any very serious work was under- 

 taken on the British species. In that year Benham published a 

 paper in the Q.J.M.S. (xxxiii. p. 187 et scq.), which dealt in detail 

 with Hcteroch/eta, and supplied valuable notes on Psammoryctes, 

 SjjirosjJerma, and Tuhifex. Benham records the discovery of 

 Spirosperma in the Thames and in the CherweLl, as well as the 

 occurrence of Hcterochivta, Remituhifex, and Clitellio at Sheerness. 

 While Vejdovsky, Stole, and others were doing good work on the 

 Continent, Beddard was helping forward the work at home. The 

 Monograph already alluded to was published in 1895, and showed 

 that the Tubificids then known had been grouped under some 

 fifteen or more different genera. It would be impossible, however, 

 to gather from Beddard how many of these genera were repre- 

 sented in the Annelid fauna of Great Britain, except that Pranchi- 

 ura is described as found in the Victoria Eegia tank in Eegent's 

 Park, London, and Vermiculus was found by Goodrich at Wey- 

 mouth. 



Among the many Continental writers to whom reference might 

 be made, we must pause at the names of Michaelsen, Bretscher, 

 Piquet, and Ditlevsen, since their researches are of special interest 



