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Transactions of the Society. 
of Rotifer, of the Genus Apsilus ,’ * recognised four species, separating 
them by the shape of the coronal cup ; Hudson and Gosse accepting 
— chiefly, as it appears, upon the dictum of Dr. Leidy — only A. lenti- 
i or mis Metsch. and A. hiper a Foulke. While I have never seen 
Leidy’s A. vorax, which seems to be exceedingly scarce, I have fre- 
quently taken, especially lately, A. hucinedax and A. hipera. Recently 
I have had both these strictly American species in some abundance, 
and have been enabled to observe some structural features, the 
description of which is the principal subject of this note. 
The two species, as I consider them (A. hucinedax and A. hipera ), 
were captured together from the same shallow clear- water pool near 
Trenton, N.J., where they were adherent to the leaflets of Utricularia 
and to the fronds of Biccia fluitans L., or were there entangled. After 
the plants had been in the aquarium for several days the Rotifers, 
or perhaps their progeny, attached themselves loosely to the side of the 
vessel, where they were visible to the naked eye as minute white dots. 
Apsilus hucinedax Forbes, plate VI. figs. 1, 2, 3, and 6. 
The coronal cup is obliquely truncate, if I may so express it, and 
is without the ventral, lobe-like enlargement characteristic of A. hipera . 
although the frontal opening has a somewhat reniform outline (fig. 2). 
A. lentiformis has its coronal cup with an oblique front, but its 
margin is to a certain extent cucullate, and the ganglion is on its 
dorsal wall, while the ganglion in A. hucinedax is cervical. 
Two lateral antennas are present, and seem to have been over- 
looked by Prof. Forbes. Each is situated near the base of the coronal 
cup, on the ventral side, and bears a radiating cluster of long fine 
setae (fig. 2). 
Dr. Hudson, speaking of the structure which gives A. hipera its 
specific name, says, “If A. hipera really has two stomachs, one above 
the jaws and the other below them, and each is a closed sac with 
walls distinct from those of the body-cavity, then it would not only 
be a new species but also a perfectly unique one among the Rotifera.” 
A. hipera has the two stomachs, but is no longer unique, for A. huci- 
nedax possesses a similar organisation, with a sac-like stomach in 
front of the mastax, and absolutely free and distinct from the body- 
walls ; in fact, it is in no way connected with those walls, and is in 
no part in contact with them, except as contact is produced by its 
ever active motions. It is, furthermore, a closed sac, opened only 
for the entrance or for the exit of alimentary matters. Anteriorly it 
is closed by what may perhaps be called the oesophageal ring, to 
which it is attached, and from which it is suspended in the cavity of 
the body. This oesophageal ring is a stout, muscular, ring-like mass 
protruding forward into the cavity of the coronal cup, and posteriorly 
into the proventriculus or the anterior stomach. The pro ventricular 
* Proc. Acad. Nat, Sci. Philadelphia, 1884, p. 37. 
