2 Transactions of the Royal Microscojncal Society. 
of tlie animalcule is broad, truncated, and surrounded with a wreath 
of cilia, interrupted at the mouth which is lateral. On the frontal 
plane arise four thick conical papillae, often furnished with an 
articulated bristle, especially the two anterior." Gosse says : " The 
frontal disk is large, and divided into two semicircular portions, 
round which the cilia seem to be set : yet, when they are in active 
rotation, the eye cannot discern any break in the ciliary crown. 
The centre of the front rises into a blunt cone, on one side of which 
projects a little jointed antenna, bearing a bristle at its tip." 
Mr. Gosse alludes to the discrepance between his account of the 
rotifer and Ehrenberg's, and notes the possibility of their being 
different species ; but I am constrained to believe from very patent 
errors in Mr. Gosse's observation — to be noticed farther on — that 
both naturalists examined the same species and both made dis- 
similar mistakes. Of course Ehrenberg's wonderful work is beyond 
detraction but just within criticism ; and if Mr. Gosse make a slip 
or two, these are readily condoned in the remembrance of his many 
discoveries and the exceedingly clever papers he has written for us. 
In the case of his article on Conochilus * there is internal evidence 
that its study was taken up for a short time very early in his 
microscopical career, that sketches and notes were made at the time 
from which some years after the paper was elaborated. Had the 
observations been made by the light of his later experience, the 
result had been very different, and probably this paper not written. 
Moreover, Mr. Gosse never had the immense assistance of Mr. 
Wenham, who supplies modern naturalists with an instrument 
making minute investigations as easy as reading with spectacles. 
But we neglect the rotifer. The facts are that the part where 
the " wreath of cilia is interrupted " is not the mouth ; there are 
not " four conical papillae each with a bristle," but only two short 
contiguous antennae (" calcars " of Ehrenberg) furnished with pencils 
of fine long setae, and the true oral aperture is a slit on the dorsal 
side of the rounded cone rising from the centre of the trochal disk. 
The peculiarity of this arrangement of features will be seen by 
comparison with those of an undoubted Melicertan. Fig. 1, 
PL OXLIIL, represents the upper part of a Limnias ; the ciliated 
disk is turned up and away from the observer, bringing the mouth 
aperture into view at A. Just as described by Huxley as existing 
in Lacinularia, a collar of fine cilia is seen running round outside 
and beneath the larger cilia of the disk, and this collar leads directly 
to the mouth. Food can often be seen traversing the channel 
between the coarse and fine ciha, and rapidly becoming engulfed in 
the buccal funnel. Now turning to Fig. 2 we see the mouth 
aperture on and above the disk. The finer ciliated frill is here 
within the bolder coarser one. Further, in the Melicertan (Fig. 1) 
* 'Pop. Scienco Review,' vol. i. p. 491. 
