24 



podon (of course leaving DrfjUugia carinata, fig. 6, out of 

 view), appertain more closely to Gromida. 



The foregoing view of the case as regards forms such as 

 those on Plates XVI and XYII, seems to receive a very strong 

 confirmation from certain freshwater Rhizopoda brought for- 

 ward only a few weeks ago by Greef, in a paper full of close 

 observation and close reasoning founded thereon,^ some of 

 which forms are identical with mine and certain others very 

 closely related, and which latter do actually seem to possess 

 a true central capsule. I allude to the forms falling under 

 his new genus Astrodisculus {A. ruber, A. flavescens, A. flavo- 

 capsulatus, Greef). This valuable and interesting paper of 

 Greef's opens up some new points, and, as is seen, brings to 

 notice some instructive new forms. 



Upon a species appertaining to one of the genera — Acan- 

 thocystis (Carter) , a valuable paper has likewise previously 

 appeared lay Grenacher,^ with whom, so far as his observa- 

 tions are concerned, Greef seems to coincide. Perhaps it 

 would be of advantage to English readers briefly to allude 

 to the points made out in both. 



As, however, some of the species Greef himself either de- 

 scribes or alludes to are actually identical with certain of 

 those described by myself in the preceding sections of this 

 communication, before the appearance of his paper (as well 

 as previously in a cursory manner in the ' Proceedings of the 

 Dublin Microscopical Club'), I shall, perhaps, most fittingly 

 allude to his account of them and of the forms most imme- 

 diately related in a paragraph following the diagnosis of 

 each of the species themselves under the head of " Affinities 

 and Differences." 



Not essaying, then, to place our forms under headings 

 of any of the proposed Classes or Orders, I shall simjily 

 attempt to give their generic and specific character, with 

 a view to facilitate their more speedy recognition when en- 

 countered by other observers. 



But before proceeding to do so, I would draw attention to 

 the circumstance that whilst partaking with other forms of a 

 common " heliozoan'^ or '' actinophryan" nature, there is, 

 moreover, one additional character or point of structure in 

 which the forms located in the three genera now soiight 



^ " Ueber Radiolarien und Radiolarien-artige Rhizopoden des siissen 

 Wassers," in Schultze's 'Arcbiv fur mlkroskopische Anatomie," Bd. v. 

 Heft, 4, Oct. 1S69. 



- 'Zeitschrift fiir wissenscli. Zoologie,' Bd. xix, p. 288, T. 2, fig 25. 



