542 H. S. Jennings and George T. Hargitt. 



The first two are the only ones that belong to Paramecium as now 

 understood. The third is Pleuronem'a chrysalis, the fourth Col- 

 pidium colpoda. The other four are so imperfectly described that 

 they have apparently not been recognized, save that it is clear 

 that none of them are species of Paramecium. Ehrenberg further 

 described as "Loxodes bursaria" the animal which is now con- 

 sidered one of the well established species of Paramecium (P. 

 bursaria). 



Perty ('52) described P. griseolum and P. aureolum, but the 

 descriptions are so poor that the animals can hardly be recognized. 

 The former according to Maupas ('83, p. 451) is a sDecies of Cryp- 

 tochilum. The latter has apparently not been placed. Perty's 

 P. versutum is P. bursaria Ehr., according to Claparede et Lach- 

 mann ('68, p. 36). 



Claparede et I.achmann ('68) add to the list of species P. 

 putrinum, P. inversum, P. microstomum, P. glaucum and P. ovale. 

 P. inversum, P. microstomum and P. ovale are evidently not 

 species of Paramecium, as at present understood. P. glaucum 

 was based upon imperfect observation of a single marine speci- 

 men, which bore no resemblance to any form of Paramecium 

 now known. Paramecium putrinum is still an accepted species 

 of this genus, though perhaps with little justification, as we 

 shall see. 



Kent ('82, p. 488) describes Paramecium marina, a marine 

 form with but a single contractile vacuole, in the rear. It seems 

 not to have been seen again; in any case it evidently does not 

 resemble the animals with which we are dealing, which all have 

 the two contractile vacuoles. Gourret et Roeser ('86) describe 

 Paramecium pyriforme, a marine form, pear-shaped, flattened 

 dorsoventrally, broad and rounded behind, with a caudal tuft of 

 long cilia; mouth large and open and furnished with prominent 

 membrane-like lips. Biitschli ('89, p. 1711) doubts the cor- 

 rectness of this description and holds that the species is not a well 

 based one, and it is not accepted by Schewiakoff ('96). In any 

 case, it clearly has nothing to do with the animals here studied. 

 Paramecium trichium was described by Stokes ('88) ; it is said by 

 Schewiakoff ('96, p. 343) to be the same as P. putrinum CI. et L. 



