33 



Localities. — In pools near Carrig mountain, county Wick- 

 low, and in county Westmeath ; rare. 



Affinities and Differences. — This form is readily and at once 

 distinguishable from A. turfacea (Carter) by its considerably 

 smaller size, short tapering and pointed spines, of one kind 

 only (not elongate, hardly tapering, bifurcate, and of two 

 dimensions). It is, likewise^ far more usually devoid of 

 chlorophyll-granules than A. turfacea, nor are they ever 

 seemingly present in the dense quantity which ordinarily 

 characterises that far more striking species. The pseudopodia 

 do not seem to be so delicate in my form, at least they are 

 usually more readily noticed than in A. turfacea. 



Its points of difference from Greef's new sj)ecies A. spini- 

 fera^ are not so manifest at first sight, but on closer com- 

 parison the two forms seem abundantly distinct. That sjjecies 

 seems pretty nearly to agree with the present in dimensions 

 (though apparently averaging a little larger), as well as in the 

 radial spines being slender and pointed, but in it the spines 

 are much longer, far finer, and much more elongate, and 

 more acute. In A. Pei'tyana the spines are in length not 

 more than a fifth or sixth part of the diameter of the body, 

 whilst in A. spinifera they seem to be in length about three 

 fourths of the diameter of the body. They agree in having 

 a discoid base (Fussplattchen), as do, so far as we know, 

 indeed all the species referable here. In my form there never 

 appear any colouring granules except green, never yellow 

 bodies (" yellow cells " ?) like those often occurring in Greef's. 

 Further, I have never seen in the former any indication of the 

 central vesicular body (representative of " central capsule" ?) 

 which forms a distinguishing feature in the latter. I have 

 never, indeed, myself seen Greef's form, but I cannot enter- 

 tain a doubt as to its complete distinctness from mine. 



As regards other described or figured forms I have already 

 (p. 255) referred to its resemblance to Actinophrys brevicirrhis^ 

 (Perty) ; if, indeed, we conceive for a moment the pseudo- 

 podia absent from my figure, and assviming that the rays 

 bordering the figures given by Perty, may be actually spines, 

 not pseudoj)odia, the resemblance to Perty^s is certainly 

 greater than to any other published figure I know of; but 

 the very great uncertainty due to the insufficient account 

 given by him of his animal fully justifies my appropriating 

 to this species a distinct name. 



But in contrasting my form with Greef's A. spinifera, and 

 on reading over his very interesting account of that species, 



1 Loc. cit., p. 493, t. xxvii, 6gs. 20—23. 



2 L. c, p. 493, t. xxvii, figs. 20—23. 



VOL. X. NEW SER. C 



