26 



region seems to me to be in both quite alike in this regard. 

 But it further appears to me to be indisputable that (in H. 

 Fockii, or Poiupholyxophrys punicea, for instance), there is 

 no capsule enclosing the globular central portion — first, 

 because it cannot be seen when crushed or otherwise — se- 

 condly, because the margin of the inner globular region 

 sometimes shows pulsating vacuoles (in H. Fockii), like those 

 of Actinophrys or Actinosphaerium — and thirdly, because 

 crude food is incepted into it — all which could not happen 

 Avere theie a rigid ' capsule' (even though minutely ' perforated' 

 for the passage of pseudopodia) enclosing it. 



If this outward boundary of the inner globe in Hetero- 

 phrys Fockii be truly the homologue of the " central capsule," 

 Avith hoAvCA'Cr delicate a wall, then the same part in Astro- 

 disculus must have a like signification, and in that case must 

 not, surely, the central globe represent rather the " inner 

 vesicle" (" Binnenblase") ? 



Nor can this outer region, as it seems to me, be sup])osed 

 to be truly the same thing, that is homologous Avith, that 

 sarcode-layer, attributed by Wallich to the Polycystina — ibe 

 " chitonosarc" Wallich — Avhich film of sarcode he supposes 

 to be formed by the universal coalescence of the bases of the 

 pseudopodia themselves.^ In the forms now described, this layer 

 is not formed by the coalescence of the pseudopodia, for these, 

 taking origin from the inner region, pass out directly through 

 the outer, Avithout the least appearance of any confluence. 



The other heliozoan genera forming the subject of Greef s 

 and my oavu communications (along with Actinophrys sol) do 

 not present the character of tAVO difibrentiated portions of the 

 sarcode body. This appears to be similar throughout, but, as 

 the case may be, in the ncAv genera enclosing or surrounded by 

 characteristic structures. 



The following, then, may serve as diagnostic characters of 

 the several forms brought forAvard : — 



Genus, Acanthocystis (Carter.) 



Generic Characters. — Rhizopod composed of two distinct 

 sarcode regions, the inner dense, hyaline and with or without 

 colouring granules, of a globular and somewhat rigid figure, 

 the outer colourless, soft, and delicate [sometimes difficult to be 

 discerned), bearing a number of more or less elongate siliceous 

 spicula discoid at the base and arranged in close approxima- 



' Wallidi "Oil the Polycjstiiia," in 'Quart. Jouru. of Micr. Science,' 

 vol. V, N. S. page 71. 



