434 C. F. ROUSSELF.T ON CYRTONIA TUBA. 



movement of the large cilia on the ridges at the sides form 

 qnite a feature of the head, simulating auricles by their vigorous 

 action. The trochal disc is highest and somewhat bent over on the 

 dorsal side, and slightly concave in the centre. I could detect no 

 sense organs on the disc, but a chain of ganglia seems to run all 

 round below the surface of the corona, three of the ganglia being 

 rather conspicuous near the dorsal edge. The secondary wreath 

 surrounds the corona below the primary, and broadening on the 

 ventral side, turns downwards almost at riglit angle to enclose a 

 sub-square space, in the centre of whicb the densely-ciliated buccal 

 orifice is situated. The exact arrangement will best be seen from 

 the figure, if it be understood that the lower part of the drawing is 

 in a plane at right angles to the corona. The buccal funnel leads 

 to a heart-shaped mastax of moderate size, to which are attached 

 two large pear-shaped glands (salivary glands ?). The troplii 

 (Fig. 3) are of the submaleate type, with eight or nine teeth in 

 each incus ; in the figure of the jaws the unci and rami are, of 

 course, not drawn in their natural position. The rami, as 

 frequently occurs in Rotifers, are bent at right angles to the 

 fulcrum, and it is, therefore, impossible to give a natural front 

 view of all the parts on a flat piece of paper. In comparing 

 figures of jaws of Rotifers with the structures themselves this must 

 be borne in mind. 



A slender oesophagus leads to a capacious thick-walled stomach, 

 the cells of which are very large and nucleated ; then follows the 

 thin-walled and densely-ciliated intestine, which opens on the 

 dorsal bide just behind the foot. Large rounded gastric glands 

 are attached to the upper part of the stomach as usual. 



Below the centre of the trochal disc is situated the small brain 

 cairying a small spheiical crimson eye ; two nerve threads run to 

 the dorsal antenna, which is double and situated on a conical 

 prominence below the head, and two further threads, one on each 

 side, connect the lateral antennae, situated low down on the sides of 

 the body on little prominences, which become visible on a dorsal 

 or ventral view. Lateral canals, with the usual glandular thicken- 

 ings and vibratile tags, as well as an ample contractile vesicle, are 

 also present. On the shoul.ier on each side there is a small 

 granular mass or organ, apparently connected with the lateral 

 canals, not usually found in Rotifers, the import of which is not 

 quite clear, and similar masses are seen at the sides, near the 

 middle of the body. The ovary is a single broad band on the 



