56 BRITISH PEESHWATBIi HELIOZOA. 



4. Acanthocystis brevicirrhis (Perty). 

 (Plate LXIV, fig. 4, LXIX, fig. 1.) , 



Actinophrys brfvicirrliis 



Perty Zuv Kennt. klein. Lebensformen, 1852, p. 159, pi. viii, f. 7. 

 Acanthocysf is perty ana 



Abchbr Qrt. .Jrn. Micr. Sci. (n.S.) IX, 1869, p. 252, pi. xvi, f. 1 ; non 

 Penard Heliozoaii-es, 1904, p. 248, fig. 

 Acanthocystis paludosa 



West J. Linn. Soc. Zool. XXVIII, 1901, p. 340, pi. xxx, S. 32, 33. 

 Acanthocystis / 



Leidy Rep. U.S. Geol. Surv. XII, 18'79, p. 270, pi. xliii, fe. 14-16. 



Body of median! size, spherical, liaYing a double 

 outer investment, the inner portion consisting of a 

 thin layer of small silicious scales, the outer portion 

 consisting of numerous, short, pin- or thorn-like spines 

 attached by their enlarged bases either radially or 

 divergently ; plasma colourless or greyish, often con- 

 taining numerous green chlorophyll cells, also numerous 

 granules and food particles ; endoplasm not clearly 

 differentiated, placed eccentrically, containing a central 

 granule ; nucleus single, grey in colour, placed eccen- 

 trically, usually concealed from view by the plasma 

 and its contents; contractile vesicle single, large; 

 pseudopodia long, tenuous, graniiliferous. 



Diameter of envelope without the spines 30 /x to 

 about 50 ju, (Penard 18 ^a to 40 /x). Length of spines 

 5 /x to 12 /x. 



ITahihit. — Lakes, ponds, ditches and quiet parts of 

 rivers and streams. 



Di.s/rrt/fitovi.— England.— Shelf and Ilkley {G. 8. 

 Wed); Sheffield District (Broim) ; W. Yoi'kshire; 

 Derbyshii'e {i>ruvni); Hornsea Mere, Lincolnshire; 

 Thames at Weybridge, Surrey. 



Scotland. — Aberfoyle ; Craigcaffie ; Ben Ledi ; Pt. 

 Patrick {Ihvirii). 



LiELAXi). — Carrig Mt., Wicklow {Jrrli,er). 



