RECENT MEMOIRS ON FRESHWATER RHIZOPODA. 351 



remain in mutual coherence, and could hardly but often get 

 removed and lost. 



I fancy the so-called Astrodiscuhis radians, Greeff, cannot 

 belong to the genus, but it more likely appertains to 

 Acanthocystis. 



Astrococcus rufus, Greeffi (PI. XXI, fig. 2), 



is described as possessing a " reddish-brown globular body, 

 surrounded by a hyaline, colourless, cortical stratum, in and. 

 on which dark shiny granules move about vigorously. 

 The colour of the inner substance is caused by the presence 

 of numerous minute pigment-granules. Upon pressure 

 larger hyaline granules are ejected from the interior, similar 

 to the pale granules of Acanthocystis, only smaller.'" The 

 author could not discover " a single larger nuclear structure. '^ 

 He describes the pseudopodia as " fine and linear, emanat- 

 ing from the reddish-brown body, passing outwards through 

 the hyaline cortex, and mostly shorter than the diameter of 

 the body." Along the pseudopodia minute granules could 

 be seen in active movement up and doAvn. 



These are the whole of the jjarticulars as regards this 

 form communicated by the author, called in his memoir 

 Astrococcus 7'ufus, but in the explanation of the plate re- 

 ferred to as Astrococcus rubescens. Granting the validity 

 of the author's own genus Astrodisculus, one is somewhat at 

 a loss to see why he makes a new genus for the present 

 form (enclosed by a " hyaline colourless cortical stratum ") 

 unless he had become satisfied that in Astrodisculus the 

 outer stratum was truly siliceous (which still I fancy appears 

 doubtful, as I have mentioned), and that that region here Avas 

 not so. As regards the statement that he did not find a 

 nucleus, there cannot be much doubt, arguing from analogy, 

 but that the carmine solution Avould have disclosed it. 



Heterophrys, Archer. 



After giving my own conception of this doubtless necessary 

 and sufficiently Avell-fouuded genus,^ Hertwig and Lesser 

 draw attention to some points in which they are unable to 

 concur with my views as to structure and nature of some of the 

 parts. As regards thepresumed absence of anucleus, I had long 

 since found out my oversight, but in extenuation I must say it 

 is a part of the organization extremely difficult to discern \ 

 hoAvever, the application of Bealc's carmine fluid rarely fails to 

 disclose this body, though having to be alloAA^ed to act for 



' Greeff, ' Schultze's Archiv,' Bd. xi, p. 27, t. ii, f. 19. 

 ' ' Quart. Joufn. Micros. Sei.,' vol. ix, p. 267; x, p. 107. 



