104 BRITISH FBESHWATER EHIZOrOPA.. 



always emit its pseudopodia from one and the same 

 point on its surface is a puzzle which Archer en- 

 deavoured to unravel without coming to a' definite 

 conclusion, except that the statement must have been 

 made in error owing to the extreme thinness of the 

 pellicle which renders it almost invisible. Possibly, 

 however, Claparede & Lachmann knew of this pellicle 

 but did not consider it to be of a sufl&ciently pro- 

 tective nature to serve as a "cuirass." Two species 

 were included in his genus, P. ci/lindrlca and P. 

 sphasrlca. They do not, however, belong to the same 

 genus, the first being considered by Penard to be most 

 probably a Diaphoropodon, and the second appearing 

 to be identical with "Gromia hyalma," as Ehrenberg's 

 species was then known. In view of this uncertainty 

 and of the fact that the definition of the genus 

 Plagiophrys, so far as regards this species, is in- 

 correct, we cannot well adopt for it Claparede & 

 Lachmann's name, which should be relegated to the 

 first of the two species which they describe, namely 

 P. cylindrica. 



The next name, Lecytliium, was proposed by Hertwig 

 & Lesser in 1874, and the only species which they 

 include in it is L. Iiyalinum. They give references to 

 former descriptions of the species, and there cannot 

 be any doubt as to its identity. The generic name 

 Lecytliium is therefore here adopted. 



Although it is unnecessary to pursue the matter 

 further it may be of interest to point out that Platoun, 

 the next name which has been considered a synonym, 

 is of uncertain application ; that it was almost imme- 

 diately followed by Ghlamydophrys, which would be the 

 name to adopt should Lecythium not stand, and that, 

 even should it fail, we need not fear having to use 

 either of the two uncouth names next proposed. 

 Troglodytes and Phonergates, as both are pre-occupied, 

 Baileya being the next available name on this some- 

 what long list. 



