210 Proceedings of the Royal Physical Society. 
Whether the hypothesis put forward in this paper—that all these amcebze 
are of one species only—will prove to be a fact, or whether each type will 
eventually be shown to be a distinct species, is for the future to decide. 
In the meantime, this paper may help those interested in the study of 
A. proteus to work onwards from the differences, without having to refind 
them for themselves, only then to discover that they have no longer time to 
proceed with such a problem. 
SUMMARY. 
1. The amcebe passing under the name of A. proteus may be divided into 
three “types,” herein designated as 4. proteus X, A. proteus Y, 
A. proteus Z. 
2. That these three “types” should not be given new specific names until 
there is more certain proof that they are distinct species, rather than 
phases in the life-history of one species of amceba. 
3. That if, however, it be proved later that these amcebze can be separated 
into distinct species, older names should be preferred to new ones— 
thus A. proteus Pallas (XY), A. princeps Ehrenberg (Y), A. nobilis 
Penard (Z); or, A. proteus Pallas (Y), A. proteus Pallas, var. 
granulosa (Y), A. nobilis Penard (2). 
4, Scheeffer’s classification into raptorial and granular ameebe is very useful, » 
but if used with the suggestion set forth in this paper, the so-called 
“species” would have to be rearranged. 
Raptorial amcebe A. proteus Pallas (A. proteus X). | | 
A. proteus Pallas, var. granulosa (A. proteus Y), or 
Granular snare} A. prunceps Ehrenberg (A. proteus Y), and , 
A. nobilis Penard (A. proteus Z). 
(Issued separately, 4th October 1919. 
