We have the theorem (I I, v; m, n) (/l l, v l; ml, n i) - (Il l, P 1; m l, n ') (/l, v; m, n) = (11, vl; ml, ni); where 1 /l1= (ml +m-1) ml (/l +nlv) - u-2 Cu '+nvl) 1 1 m-1 1 m1-1 vl =(n -n)vv-E ml / lY- m /lv, m i =7111+m-I, n1=nl+n, and we conclude that qua " alternation" the operators of the system form a " group."
Vl `?la 4 ?
Absolutely restricted to the Old VL orld, with 9 genera comprising about 40 species.
The larva is seen in optical section, and its distinguishing feature is the ciliated lobed band (vl, sl, dl), which corresponds to the pre-oral ciliated band of a trochosphere-larva..
EXX vL-e v, to imitate the Greeks, who were known as "EXX vEr, after "EXX77v, the son of Deucalion).