RKCENT MKMOIRS ON FKESHWATEK RHIZOPOUA. 123 



consists of a more or less richly granular protoplasm. The 

 authors never noticed any vacuoles, but could readily discern 

 the nucleus, which always appeared, on application of acetic 

 acid, to be homogeneous and a nucleolus could not be perceived. 

 The pseudopodia are mostly few and homogeneous. In these 

 characters they differ from Claparede's PI. cyUndrica, where 

 they are very numerous, and granuliferous. In the present 

 form they are rather quickly projected and withdrawn. The 

 authors give the dimensions as follows: Length, 0'035 mm., 

 breadth at middle, 0"025 mm. j thus considerably smaller than 

 Flag. cyUndrica. 



Plagiophrys scutiformis, Hertwig et Lesser^ (PI. VIII, 



fig. 10), ^ 



is distinguished from the preceding by its peculiar shield- 

 shaped figure, owing to its being so strongly compressed j 

 otherwise as to body-structure, pseudopodia^ nucleus, this 

 agrees with the preceding. Its dimensions are greater. 

 Length, 0'06 mm., breadth, 0"04 mm. 



I must myself quite agree with the authors in holding this 

 in itself as a distinct species from the foregoing and others. 



I perceive by a note appended at the end of their work 

 that the authors do not regard the form I recorded as oc- 

 curring in this country and referred to Plagioplirys sjyherica, 

 Clap, et Lachm.j as truly identical therewith, but as probably 

 the same species as their PL sacciformis , though they quite 

 agree in my interpretation of its general structure. No 

 doubt our form comes very near PI. sacciformis, nor have I, 

 as little as these authors, as yet been able to recognise in our 

 form the presence of any contracted vacuoles. But the 

 action of such may sometimes be so slow and their size so 

 minute, whilst even their existence may be obscured by 

 the density of the surrounding granular plasma, that their 

 presence or absence is often very difficult of determination. 

 Claparede's and Lachmann's figure is so insufficient, and their 

 description so brief and vague, that the absolute determina- 

 tion of what their species actually may be is sufficiently 

 difficult. 



I am glad they too agree with my conjecture that the 

 second form^ which I drew attention to, and have tried 

 to represent on the same plate, is a distinct species. Having 

 already at large adverted to it, I may only here avail myself 



1 Loc. cit., p. 115, t. Ill, f. 2. 



- ' Quarterly Journal of Micr. Sci.,' vol. XI, p. 146. ' Proc. Hoyal Irish 

 Academy,' ser. ii, vol. i. 



VOL. XVII. NEW SER. I 



