These septa are, however, rather incomplete and are not fastened to the gut; and, as in Acanthobdella, the nephridia are embedded vv FIG.
-- ??ol ltu Thph vv orzani.y„L'uu?aso s ??ls Lu-o.?
Coelomic space in Balano- vv, vessel.
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."