143 



It is observable, however, that the presence of vibratile 

 cilia in the first embryonic form is a character of little 

 importance, and cannot serve as the basis of a natural 

 classification. 



Eemarks on Opalina and its Contractile Vesicles, on 

 Pachyuermon and Annelidan Spermatophors. By 

 E. Ray Lankester, B.A. Oxon. Plate IX. 



In examining the anatomy of oligochaetous Annelids, I 

 have necessarily met with certain species of Opalina, that 

 curious mouthless genus of Infusoria the life history of 

 which, like that of so many of the class, is as yet quite un- 

 known. Some notes on the Opalina Naidos of Dujardin, 

 which abundantly infests the Nais serpentina, may not be 

 uninteresting ; at the same time, I offer some evidence as to 

 the nature of the bodies which Professor Claparede considered 

 to be Opalinoid parasites, and termed Pachydermon, figuring 

 them from two species of the oligochaet Clitellio ; but 

 which I think, from the characters of some observed by me 

 in another worm (namely, Lhnnodrilus) must be considered 

 as packets of spermatozoa or spermatophors. 



Opalinje. — The genus Opalina has sometimes been made 

 to include those pyriform ciliated animalcules which swarm 

 in the rectum of the common tadpole and in similar situations, 

 called Bursaria Ranee by Ehrenberg ; but these forms should 

 rightly be separated from those so frequently found in both 

 marine and freshwater Annelids, from which they differ 

 materially, as pointed out by Claparede in his work with 

 Lachmann on the Infusoria. 



The simple structureless body of these first-named para- 

 sites has really very little in common with Opalina, properly 

 so called — an abundance of highly refrangent granules being 

 the only differentiated porticms of its substance (PI. IX, fig. 

 9), no trace of the nucleus and contracted vesicles, nor of 

 the furrowed cuticle of true Opalina being observable. It is 

 not improbable that these swarming ciliated flakes of sar- 

 code — for they are nothing more — may undergo subsequent 

 metamorphosis of the most extreme character ; but what is 

 true of them does not apply to veritable Opalina. 



Opalince of the type I am about to describe have been 

 observed by Dujardin, Schultze, Schmidt, Stein, and Clapa- 

 rede in various worms. Thus we have Opalina Naidos, 



