A New Type of Infusorian : Arachnidiopsis paradoxa. 289 



orders;* the Ciliata because tliey possess cilia, the Tentaculifera 

 because in 'their adult state they possess Tentacula. Now we 

 have here, in Arachnidiopsis or Araclinidium, neither cilia nor 

 tentacles (this term being considered in the sense of Tentacula as 

 applied to Acincta). It will, then, be hardly possible to refer our 

 small group to either of these two orders ; bvit our knowledge 

 about these organisms is still too incomplete to allow of the creation 

 of a special order, and it is to be hoped that more representatives, 

 of this rare and interesting type will be found in sufficient, 

 quantities to allow of a more adequate study. 



Since the above was written the organism described has beer» 

 met with in a new station, and, although not in alnmdance, in 

 sufficient numbers to allow of definite conclusions about some 

 points previously obscure or doubtful, e.g. : — 



{a) There is no micronucleus. 



(b) The large spheroidal body is not covered or composed of the 

 same rod-like particles as are to be seen at the anterior part of 

 the animal, but is formed by Bacteria, such as are to be found in 

 Pelomyxa, collected at the surface of, and partly inside a muci- 

 laginous pellet. 



(c) Food has been repeatedly found in the body in the shape of 

 small algse, etc., which are digested in the ordinary way, and whose 

 remains may be expelled by the opening of the body near the 

 posterior extremity. 



* In his "Faune infusorienne des environs de Geneve" (M^m. Instit. Nation. 

 Genevois, xix. 1901) Roux created a third order, that of the Mastigotricha, for a 

 single species, Monomastix ciliatus, which, along with a complete ciliation of the 

 surface of the body, is in possession of a long, anterior flagellum. But having 

 found more recently this Monomastix in this neighbourhood, I came to the 

 conclusion that Roux's Monomastix is iu fact a Trachelophyllum, a genuine 

 holotrichous Infusorian, in which this sort of beak, which is characteristic of some 

 species of that genus, is protracted into a very long thread ; this thread then 

 curves behind, and floats along one of the sides of the body, undulating weakly at 

 tirnes under the influence of the currents produced by the cilia. It is also, I think, 

 quite in the vicinity of Trachelophyllum that we must locate Stokes' Ileonema 

 dispar (Silliman's Amer. Journ., xxviii, 1884), an Infusorian also very nearly 

 related to Monomastix. 



