226 



)r. J. D. Macdonald on the Polycystina. 



particulars similar to that of the Foraminifera ; but where this 

 not the case, it is simply continuous or only augmentative. 

 ^Though our knowledge of the Polycystina is yet very limited , 

 the two modes of growth here indicated suggest their distri- 

 bution into two corresponding sections, thus : — 



Polycystina. 

 Rhizopoda furuislied with a siliceous spicular or fenestrated framework. 



\ bimple or continuous . . \ r? ^ • ; • 

 J ^ j JiKCi/rfiaimn. 



/ JDV concentric accessions { /, •' 

 { •' Astromma. 



Growth of 

 sarcode 



Now that the surface pelagic life of the Polycystina is a 

 matter of fact, we can readily account for the occurrence of so 

 many interesting forms in guano. 



Fiff. 1. 



Fig. 2. 



Astromma Yelvertom. 



Front view. 



Side view. 



Figs. 1 & 2 are respectively a front and a side view of a 

 species of Astromma with three radiating lobes, A. Aristoteh's 

 having four. As the species appears to be new, I have named 

 it Astromma Yelvertom. 



H.M.S. 'Lord Warden.' 

 Corfu, June 24, 1871. 



