On the Rotifer Conochilus volvox. By Henry Davis. 3 
we have the small antennae widely separated, one on either side of 
the body ; in Conochilus (Fig. 2) these are close together and 
placed on the crown of the head. 
The slit of the mouth being towards the dorsal side makes 
another departure from the Melicertan type ; but it is worthy of 
notice that the " set " of the mastax gizzard "), with its lower 
narrow ends pointing to the ventral side, also the position of the 
ovary and other internal parts, are precisely as if the oral aperture 
were opposite to its true position, and quite favours the fancy that 
Conochilus was once a Melicertan ; that the circumstance of mutual 
agglomeration had necessitated the displacement of the opening to 
the mouth, which had drawn through the usual notch in the ventral 
edge of the disk (still traceable), carrying the fine ciliated collar 
and antennae with it well over to the middle of the disk. 
The obscure division of the alimentary canal into three parts, as 
seen by Huxley in Lacinularia, is very plainly marked in Conochilus, 
especially when they are filled with difierently coloured food, or 
with carmine, indigo, &c. The contents of each division does not 
appear to filter gradually from one to another, but empties suddenly, 
thus : — the contents of the rectum being discharged in one pellet, 
after a few seconds it is replaced by the full charge of the central 
compartment of the alimentary canal, and this again by all in the 
stomach, which at once begins to fill up from the food passing from 
the mastax. 
The usual " tremulous tags " — four pairs — I see in Conochilus, 
but no contractile vesicle. The eyes are very fine ; each a clear 
colourless globe imbedded in a red pigment — they seem fixedly 
directed upward and outward. 
The more we examine and understand the rotifers, the farther 
we seem from a basis on which to found a satisfactory scheme of 
classification. What we might well consider the best as applied to 
the " builder " rotifers by Gosse breaks down entirely with Cono- 
chilus. It cannot possibly be ranked with Megalotrocha (itself 
plainly a Lacinularia), and is but distantly related to his family 
Melicertadse. It comes half-way between the Floscules and the 
MeKcertans, having the oral aperture situated and armed like that 
of the former, but with the active ciliated disk of the latter. 
Surrounded by the clear jelly in which the little animals live 
may be found in nearly every well-grown colony two distinct kinds 
of eggs ; more rarely a third smaller sort is seen (male egg. Fig. 5). 
The female egg is transparent, nearly colourless, and, when far 
developed, the foetus with its large mastax may be plainly seen 
within (Fig. 5). The smaller egg is equally clear, and reveals the 
male very neatly packed up ; but, even at this tender age, restless 
and gymnastic beyond belief. The other kind of egg (" ephippial " 
of Huxley) is somewhat larger than the ordinary female egg, of 
B 2 
