ACTINOCYATHUS. 



[ 14 ] 



ACTINOPHRYS. 



vularia by Suhr (Kiitz. Tab. Phyc. 31, 

 fig. 2). 



ACTINOCY'ATHUS, Kent. A genus 

 of Infusoria. 



BIBL. Kent, Man. Inf. 



ACTINOCYC'LUS. A genus of Dia- 

 tomacese (Cohort Coscinodiscese). 



Char. Frustules solitary, free or adherent 

 to other bodies ; disk-shaped ; valves circu- 

 lar, exhibiting cellular markings, with rays 

 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 bauds arise from undulations 

 of the surface, which are best seen in the 

 front view (PI. 25. fig. 17 b). 



A. undulatus (PI. 25. fig. 17 a) ; rays 6, 

 diarn. 1-250 to 1-1100". 



Kiitzing enumerates 34 species; some are 

 found fossil. 



Smith admits A. duodenarim (rays 12), 

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

 (rays 18) as British species referred by 

 Ehrenberg and Kiitzing to the genus Acti- 

 noptychus. These are found in the Medway. 



BIBL. Ehrenberg, Leb. KriedethiercJie-n, 

 1840, p. 57 ; Monatsber. 1844, and Mikrog. ; 

 Kiitzing, Bacillar. 1844 ; Sp. Alyarum, 

 1849; Roper, Mic. Jn. ii.; Smith, Brit. 

 Diat. i. 25, and ii. 86; Rabenhorst, Fl. Alg. 

 35. 



ACTINODIS'CUS, Grev. A genus of 

 Diatom acese. 



Char. Frustules free, disk-shaped ; valves 

 granular, with a central nucleus, and nu- 

 merous (15) linear smooth rays extending 

 from it to the margin. 



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

 1-250". In the Barbadoes deposit. 



BIBL. Greville, Micr. Trans. 1863, 69. 



ACTINOGO'NIUM, Ehr. A genus of 

 Diatonaacese. 



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 Polycystina. 



BIBL. Ehr. Monatsber. d. Berl. 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. mirabilis (PI. 53. fig. 1); 

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



BIBL. Kent, Infus. p. 227. 



ACTINOPHRYl'NA, Duj. A family 

 of Radiolarian Rhizopoda. 



Char. Body usually rounded, contained 

 in a shell or shell-less, giving off radiate 

 non-agglutinating pseudopodia, either from 

 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. 



(Acanthocystis.) 

 Pseudopodia arising from a zone near 



the circumference Trichodiscus. 



Pseudopodia arising from one side I'luyiophrys. 



Shell present. 

 Free. 



Incrusted with foreign matter Pleurophrys. 



Not incrusted, oblong. 



Orifice lateral Trinema. 



Orifice terminal Euytypha. 



Attached to foreign bodies Urnula. 



BIBL. That of the genera. 



ACTI'NOPHRYS, Ehr. A genus of 

 Actinophryiua. 



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 diffused 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 very slow ; gra- 

 nules may be seen continually 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. 7 b). Spherical, 

 colourless, whitish tentacles radiating from 

 all parts of the body; 1 or 2 contractile 

 vesicles strongly projecting on the surface ; 

 parenchyma not reticular; diam. 1-430 to 

 1-1200"; fresh water. 



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

 A. sol, but parenchyma presenting a more 

 or less regular cellular appearance; diam. 

 1-100". 



A. marina, D. As A. sol, but marine, 

 rather smaller, and movements of tentacles 

 more rapid. 



A. brevicirrhis, P. Greenish, not reti- 

 cular ; pseudopodia very short and very 

 numerous. 



A. pennipes, Cl. & L. Not reticular; 

 pseudopodia few, slender, and very long; 

 no projecting vesicle. 



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



