FRESHWATER RHIZOPODS AND HELIOZOA. BAL 
“* Acanthocystis?” mentioned and figured by Leidy in his 
Rhizopods of N. Amer. p. 270, t. xliii. ff. 14-16. It is of the 
same size, the delicate spines are exactly similar, and the in- 
dividuals were colourless or filled with bright green chlorophyll 
corpuscles. I have cbtained it from four separate localities, and 
on two occasions it was in quantity; and as it has also been 
observed from the United States, and the specimens I observed. 
showed no appreciable variation, I think it quite worthy to be 
named as a distinct animal. The same Heliozoén is mentioned 
by Scourfield (P. Z. 8S. 1897, pp. 786-789) as occurring from 
Spitsbergen. 
To a certain extent it resembles the four following species :-— 
Acanthocystis flava, Greeff, A. aculeata, Hertwig & Lesser, 
A. Pertyana, Archer, and A. spinifera, Greeff. A. paludosa is 
sufficiently distinct to need no differentiation from the first two 
species. From A. Pertyana and A. spinifera it differs wholly in 
the nature of the spines, which are much more numerous and 
delicate. The pseudopodia are few in number and granular in 
appearance as in A. spznifera, but the outer surface of the bedy 
to which the spines are attached seems to be very much firmer. 
A. paludosa also resembles A. erinaceus, Penard, 1889 (cfr. 
Schaudinn, ‘ Heliozoa’ in Das Tierreich, 1896, p. 19), but is a 
larger species with relatively shorter and more numerous spines. 
In old and dead individuals the spines readily become dis- 
engaged from the firm outer coat, and then each spine is seen to 
be pin-shaped, with a capitate base or point of attachment. 
The living animal protrudes a few long delicate pseudopodia 
which can withstand considerable irritation before being 
retracted. When the pseudopodia are fully out, the animal glides 
slowly through the water. 
Order DESMOTHORACA. 
Gen. CLaTHRULINA, Cienkowsht. 
68. CLATHRULINA ELEGANS, Cienk. in Archiv fiir mikr. Anat. 
1867, ii. p. 310, t. xviii.; Leidy, Freshw. Rhiz. N. Amer. 1879, 
p- 273, t. xliv. 
Rare: among Jsoétes and numerous alge, Llyn Ogwen, 
N. Wales. Pool near Windermere, Westmoreland. Also from 
the vicinity of Lough Neagh, Co. Armagh, Ireland; many of 
these specimens were attached in the encysted condition and had 
brown siliceous capsules. 
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