186 MR JAMES MURRAY ON 
more adapted for lake or pond life. The others are bog- or moss-dwellers, except 
C. annulatus and C. aspera, which are commonly ‘symbiotic’ with hepatics on trees. 
The Adinetadze on our list are all moss-dwellers, and casual, though frequent, in 
lochs. A. oeulata, which is not on the list, is a pond species. 
The Ploima are too numerous to be compared in detail. A large number of the pond 
species have not yet been seen in lakes, though there is no reason why they should not 
be expected sooner or later. 
The Microcodidz, active swimmers though they are, are pond species ; the Asplaneh- 
nade, Syncheetadee, and Triarthrade chiefly lacustrine. 
The host of Notommatadze are about equally divided, some of the species being 
eminently characteristic of lakes. 
The Hydatinadee and Rattulidee are most frequent in ponds, the Dinocharidee in 
bogs and ponds. 
The remaining families of loricated Ploima are fairly adapted to a lacustrine life, the 
Pterodinade among these being most restricted to ponds. In the Pleesomadze are both 
lake and pond species. 
Callidina natans, n. sp. (Plate IL. figs. 8a to 82.) 
Specific characters.—Of moderate size, whitish. Free-swimming. When swimming, 
broadest at corona, tapering to very slender foot, with slight expansion in central part 
of trunk. Rostrum long, extended forward when swimming ; lamelle apparently united 
in single large hood, as in Metopidia and Stephanops; antenna equal to three-fifths 
diameter of neck, directed backwards. Jaws very long and narrow; teeth 2/2, 2/1, or 
3/1, very excentric. Stomach large. Foot very slender, hardly tapering, one-fifth of 
total length, one-third formed by the terminal segment ; spurs minute, acute ; toes three, 
large. Food not moulded into pellets. Trunk closely plicate, in optical section elliptical. 
No processes seen on rostrum except lamelle and brush of cilia. Vibratile tags narrow, 
parallel-sided, 14 « long; three pairs seen. 
Length when swimming, 400 «; when creeping, scarcely greater. Diameter of 
corona, 90 «; of neck, 55 «; of trunk, 75 um. 
Owing to the habit of stretching the rostrum forward when swimming, the upper lip 
could not be clearly observed. The discs are large, and only separated by a small space 
(about quarter the diameter of one disc), across which stretches a hyaline membrane 
almost on a level with the discs. From time to time, as the animal turned slightly 
in swimming, a little sharp elevation was seen between the discs. This I regard, not 
as a ‘ligule’ proper, which should be an independent structure, but as probably the 
angle of meeting of the skin-folds so characteristic of the upper lip, and which form a 
similar angle in other species. 
The rostral lamelle are of rather unusual form. When fully extended they quite 
lose the appearance of being two-lobed presented by most rostral lamellze, and look like 
a hood, gently curved forward at the tip (fig. 89). 
