ARCHER—ON RHIZOPODA. 935 
Rhizopod which evidently vanishes to have its space occupied by 
the former ? Only when there are three, however, does it ordinarily all 
disappear. How do the ova originally come there? How can the 
mother rotatorian deposit her ova, ichneumon-like, within the ill-fated 
Acanthocystis, for the ‘‘lorica’’ of Carter seems intact ? 
This genus differs from Actinophrys in the possession of a skeleton, 
from Clathrulina* in the possession of two distinct kinds of loose por- 
tions of the skeleton, and not a hollow perforate globe; nor can such a 
type be referred to any of the marine genera of Haeckel, owing to the 
absence of the all-important character—the possession of a ‘central 
eapsule.”” In fact, Carter had no alternative but to make a distinct 
genus for his Acanthocystis turfacea, which species has hitherto been 
the only one known, and hence the type of the genus. 
It may not, therefore, be without interest to draw attention to a 
second ferm in a genus which, while it is shut out from the marine 
forms, has no very immediate relative in the fresh waters, at least so 
far as the characters to be drawn from the skeleton are concerned. 
The form, of which I now venture to refer to a rough sketch, fig. 1, 
has occurred to me in one or two places only, near Carrig Mountain, 
Wicklow, and at first glance I took it for a possible rotatorian ovum ; 
for, until I made a second gathering from the same source, presenting a 
greater number of examples, I had not the good fortune to find a speci- 
men with the pseudopodia extended. But a brief inspection even of 
specimens not exhibiting the pseudopodia satisfied myself that it was 
no ovum I had before me, but a true Rhizopod. In the first place, I 
noticed that the short, slender, tapering and pointed rays were not 
always vertical, but lying in various directions. I saw too, shortly, 
in some specimens, that they were readily shed, and then that they 
were capitate at the lowerend. All this could not happen were this body 
arotatorian egg. I felt at once satisfied I had before me a new form re- 
ferrible to Carter’s genus Acanthocystis, which diagnosis was fullyc on- 
firmed on finding examples copiously displaying pseudopodia. I could ne- 
ver see any trace of either ‘‘ nucleus” or vacuole. It, of course, struck me 
that this form might have been previously encountered, and that there was 
a possibility of the spines being taken for pseudopodia, which they, no 
doubt, at first resemble; and on reference to Perty’s work a form pre- 
sents itself, as has been mentioned (/oc. cit.), with which this may be really 
identical, though I fear the data afforded are by no means sufficient to 
decide this point. But if my form is, in fact, Perty’s Actinophrys bre- 
vicirriis, nothing can be more certain than that he has misappre- 
hended the characters presented, and that for a time, like myself, 
having seen only specimens with the pseudopodia not extended, he has 
mistaken the spines for pseudopodia. A further ground, too, is given 
* Cienkowski, in Schultze’s ‘“‘ Archiv fiir Mikroskopische Anatomie,” Band iii., 
Heft iii., p. 311, 1867. 
VOL. V. Paar 
