144 



Dujardin, in Nais ; 0. polymorjiha, Schultze, in Planaria 

 torva ; O. lineata, Schultze, in Nais (?) littoralis ; O. recurva, 

 Claparecle, in Planaria limacina ; O. prolifera, Claparede,^ 

 in a supposed marine Nais ; O. filum, Claparede, in Clitdlio 

 arenarius ; O. ovata, Clap., in Phijllodoce ; 0. convexa, Clap., 

 in another Phijllodoce ; 0. Pachydrili, Clap., in Pachydrilus 

 verrucosus ; O. uncinata, Schultze, in Planaria ulvce ; 0. 

 armata and O. falcifera, Stein, in Lumbricus terrestris and 

 L. anatomicus — these three species bearing hooks are placed 

 in the genus Hoplitojjhrya, Stein; whilst another species, 

 formerly known as Leucophrys stiata, is called Anoplojjhrya 

 lumbrici. At the same time, Hoplitophrya armata is sup- 

 posed by Stein to be a later development of A. lumbrici. 



Though they are common enough there appears to have 

 been doubt as to the character of OpaliuEe ; first as to the 

 nature of the vesicles which they possess, and secondly, as 

 to the nucleus. Schultze described a series of contractile 

 vesicles in his O. lineata ; and Claparede subsequently saw 

 vesicles in another Opalina, but could not succeed in wit- 

 nessing their contraction. In the species which he has most 

 lately described, however (" E-echerches sur les Annelides, 

 Turbellaries, &c., observes dans les Hebrides'"'), he states 

 that he has observed the contraction of the vesicles. 



In certain species found in Planariae a single long con- 

 tractile vesicle has been said by Schultze to exist, taking the 

 place of the series of smaller vesicles. A nucleus of vai-ious 

 size and distinctness has been described in these true Opalinse, 

 but never a nucleolus. Stein describes the nucleus of O. 

 armata as presenting oval embedded granules and rod-like 

 bodies. 



The two forms occurring in the Earthworm (O. armata 

 and O. fulcifera) , as well as 0. uncinata, from a Fianarian, 

 possess a pair of recurved booklets, which, situated at one 

 end, are believed to furnish a means of attachment, as in 

 some Gregarinae {G. Sieboldii, KoU., from Libellula larva). 

 The tooth-like body of Dysteria (Huxley, ' Quart. Journ. 

 Microsc. Sci.,' Vol. 5, 185T, p. 138) furnishes a parallel 

 development in an adult ciliate Infusorian. 



From the general statements witli regard to Opalina, ex- 

 cluding from consideration the so-called Bursaria Ranee and 

 similar species, there seems to be no reason for su]jposing 

 that they are anything but Infusoria ; the supposition that 

 they are a phase in the development of certain worms being 



' This species is peculiarly inleresUng, since it is distinctly a segmented 

 animal — as much as any Tania — presenting a chain of incomplete zooids 

 attached one behind the other. 



