2G 



THE EOTIFEEA. 



I have named these orders as follows : 



I. RHIZOTA (the rooted). Fixed when adult. 

 II. BDELLOIDA (the leech-like). That swim with their ciliary wreath, and creep like a leech. 



III. PLOIMA (the sea-worthy). That only swim with their ciliary wreath. 



IV. SCIItTOPODA (the skippers). That swim with their ciliary wreath, and skip with Arthropodous 



limbs. 



Now, the creatures contained in these orders, with a few exceptions, differ from each 

 other, first in their habits, and secondly in the following points : 

 I. In the structure of the foot. 

 II. In the arrangement of the ciliary wreath. 

 III. In the form of the trophi. 



I. In the structure of the foot. 

 (1) The Bhizotic foot is transversely wrinkled, and ends in a sort of sucking disk 

 (fig. 16) or cup (fig. 17). It is not retractile within the body, it never has telescopic 

 joints, nor is it ever furcate. 



Fig. 16. — Rhizotic f""t. 

 ( Flosculaiia campanvXata) 



Fig. 17.— Rhizotic foot. 

 i Mi Ha /in ring* ns) 



Fig. 18.— Bdelloidic foot. 

 ( Rotifer citrinui) 



.19. ■ irtopodic foot. 

 ( !'■ dalion mirum ) 



(2) The Bdelloidic foot (fig. 18), on the contrary, is telescopic, retractile, furcate, and 

 is never transversely wrinkled, nor terminated by a sucking disk. 



(3) The Scirtopodic foot (fig. 19) is unique; it is divided into two unconnected, 

 smooth, jointless styles, each ending in a ciliated expansion. 



(i) The Plowvic foot is various in shape, but is always unlike that of any other 

 order ; for — 



(a) if transversely wrinkled, it is yet retractile within the body, and almost invari- 

 ably furcate ; 

 {b) if jointed and furcate, it is not also telescopic ; 

 (c) occasionally it is absent altogether. 

 II. In the arrangement of the ciliary wreath. 1 

 (1) The Bhizotic ciliary wreath is of two forms : 



(a) The first encircles the body twice, by bending on itself; thus inclosing the 

 mouth, and having a dorsal gap between the points of flexure, figs. 20, 21. 



! i . 20. — Bhizotic wreath <" >, front view. 

 ( MeUeerta i in •■ n i 



Fig. 21. 



-Rhizotic wreath (" i, side view. 



( MillCi ril' i ll/i/i in I 



Fig. 22. — Bhizotic wreath (&), 



seen fr.nii above. 



( Floscularia campanuhtta ) 



1 In figs. 20 to 25, cw is the ciliary wreath ; pw is the principal wreath ; siv is the secondary wreath ; 

 bf the buccal funnel ; lp the lips. 



