AKACHXOIDEUM. 19 



-2. Actinosphaerium arachnoideum Penard. 

 (Plate LXVI, fig. 1.) 



i.: rii in 

 PENASD Heliozoaires, 1904, p. 137, fig. 



Body spherical, of a grey colour; ectoplasm formed 

 of large vacuoles merging gradually into the endo- 

 plasm; endoplasm granular, containing minute vacu- 

 oles and refringent particles ; nuclei placed in central 

 region, not exceeding twelve in number, usually fewer 

 than six, large, granular, containing numerous iiucleoli; 

 contractile vesicles large, one to three in number ; 

 pseudopodia of two kinds, one long, straight, with a 

 firm central axis, the other filiform, amoeboid and 

 anastomosing. 



Diameter of body 50 ^ to 90 p ; nuclei 12 ^ in 

 diameter or les* ; pseudopodia may attain four times 

 diameter of the body in length. 



Flab if at. Marshy pools. 



Distribution. ENGLAND. Delamere, Cheshire (Cash). 



Cash describes the plasma of the individual shown 

 on Plate LXVI, fig. 1, as greenish owing to the con- 

 tained chlorophyll particles mixed with some of a 

 golden yellow ; the contractile vesicle had a period of 

 about one minute. 



Unless the anastomosing pseudopodia were expanded 

 an individual of this species would probably be taken 

 for Actinosphserium eicfihornii. 



Genus 2. AGTINOPHRYS Ehrenb. 

 Actinophrys EHBENBEEG Abb. Akad. Berl. 1830, p. 42. 



Body spherical, contained in a smooth membranous 

 envelope; plasma containing numerous vacuoles, the 

 largest situated in the zone of the ectoplasm ; zoo- 

 chlorellse often present living symbiotically ; nucleus 

 single, placed centrally ; contractile vesicle large, 



