ACTINOCYATIIUS. 



[ 14 ] 



ACTINOPHRYS. 



rularin hy Sulir (Kiitz. Tah, rhyc. 31, 

 fig. 2). 



ACTINOCY'ATHUS, Keut.— A genus 

 of Infusoria. 



BiBL. Kent, Man. Inf. 



ACTINOCYC'LUS.— A genus of Dia- 

 tomaceee (Coliort Cosciuodiscese). 



Char. Frustules solitary, fi'ee or adherent 

 to other hodies ; disk-shaped ; valves circu- 

 lar, exhibiting cellular markings, with ravs 

 or bands radiating from the centre, which 

 is free from the cellular appearance; no 

 internal septa ; marine. 



The cellular appearance arises from the 

 existence of depressions upon the surface. 

 The radiant bands arise from undulations 

 of the surface, which are best seen in the 

 front view (PL 2o. fig. 17 b). 



A. undulatus (PI. 25. fig. 17 a) ; ravs G, 

 diam. l-2.-i0 to 1-1100". 



Kiitzing enumerates 34 species; some are 

 found fossil. 



Smith admits A. duocknanns (rays 12), 

 A. sedenarius (rays 16), and A. ocfodenftrius 

 (rays 18) as British — species referred by 

 Elirenberg and Kutzing to the genus Adi- 

 noptychus. These are found in the Medway. 



BiBL. Ehrenberg, Leh. Kriedethienhen, 

 1840, p. o7 ; Monatsber. 1844, and Mikroy. ; 

 Kutzing, Bacillar. 1844 ; Sp. Alyarnm^ 

 1849 ; Roper, 3Iic. Jn. ii. ; Smith. Brit. 

 Diat. i. 25, and ii. ^'o ; Rabenhurst, Fl. Aly. 

 35. 



ACTINODIS'CUS, Grev.— A genus of 

 Diatomacete. 



Cliar. Frustules free, disk-shaped ; valves 

 granular, with a central nucleus, and nu- 

 merous (15) linear smooth rays extending 

 from it to the margin. 



A. Barhadensis (PI. 36. fig. 22). Diam. 

 1-250". In the Barbadoes deposit. 



BiEL. Greville, Mhr. Trans. 1803, 69. 



ACTINOGO'Nimi, Ehr.— A genus of 

 DiatomacefB. 



Char. Prismatic, frustules not forming 

 a filament, subspherical, with 7 or more 

 angles. 



A. septenarium (PI. 18. fig. 8). With 7 

 angles. Found fossil in Barbadoes earth, 

 with Polvcvstina. 



BiBL. 'Ehr. ILmatshcr. d. Bnrl. Ak. 1847 ; 

 Ann. N. Hist. vol. xx. p. 127. 



ACTINOM'ONAS, Kent.— A genus of 

 Infusoria, Ord. Flagellata (Radio-flagellata, 

 Kt.). 



Char. Resembles a stalked Actinophrys 

 with a long anterior flagellum ; neither test 

 nor central capsule. 



2 species: — A. mirahilis (PI. 53. fig. 1); 

 diam. 1-2000". A.pusilla; diam. 1-3250". 



BiBL. Kent, Infus. p. 227. 



ACTINOPHRYl'NA, l)uj.— A family 

 of Radiolarian Rhizopoda. 



Char. Body usually rounded, contained 

 in a shell or shell-less, giving off radiate 

 non-ngglutinating pseudopodia, either fiom 

 the entire surface, or from parts only ; spi- 

 cules and spines absent. 



The genera may be divided thus : — 



Shell absent. 



Pseudopodia arising from all parts of 



the surface Actinophrys. 



(^Aoanihocysiis.) 

 Pseudopodia arising from a zone near 



the circumference Trichodiscus. 



Pseudopodia arising from one side IHugiopkrys. 



Shell present. 

 Free. 



Incrusted with foreign matter Plciirophrys. 



Not incrusted, oblong. 



Orifice lateral Trinema. 



Orifice terminal y.urjhjpha. 



Attached to foreign bodies JJrnuLa. 



BiBL. That of the genera. 



AOTI'NOPHRYS, Ehr.— A genus of 

 Actinophryina. 



The species of Actinophrys are found in 

 both fresh and salt water. The body ex- 

 hibits contractile vesicles, mostly near the 

 margin, but sometimes more ditfused and 

 giving it a cellular appearance. Conjugation 

 has been repeatedly observed ; but authors 

 are not agreed upon its import. The move- 

 ment of the pseudopodia is veiy .slow : gra- 

 nules may be seen, contiiuially moving in 

 them, as in the Gromida and Foraminifera ; 

 but the circulation is much slower, and 

 requires great attention and a high power 

 to render it visible. 



A. sol, E. (PI. 30. fig. 7i). Spherical, 

 colourless, whitish tentacles radiating from 

 all parts of the body; 1 or 2 contractile 

 vesicles strongly prujectiug on the surface; 

 parenchvma not reticiJar; diam. 1-430 to 

 1-1200"; fresh water. 



A. Eichornii, E. (PI. 30. fig. 7 a). As 

 A. sol, but parencliyma presenting a more 



appearance; diam. 



or less regular celhdar 



D. As A. sol, but marine. 



1-100' 



A. marina.^ 

 rather smaller, and movements of tentacles 

 more rapid. 



A. hreririrrhis, P. Greenish, not reti- 

 cular ; pseudopodia very short and very 

 numerous. 



A. pcnnipes, CI. & L. Not reticular; 

 pseudopodia few, slender, and very long; 

 no projecting vesicle. 



A. viridis,'E, (PI. 30. fig. 6). Spherical ; 



t 



