In the Surirella Venus (Pl. I. fig. 4.) the epidermis possesses manifestly muscular strength, and when the muscular bag opens itself, it opens the cuirass, and by its contraction, it closes entirely the valves.
In the Cosmarium deltoïdes (fig. 19.) the two valves of the cuirass separate themselves by the muscular strength of both bladders (a.), passing through the holes of the cuirass, and uniting themselves again, as soon as the bladders are drawn back. In the Cosmarium sinuosum (fig. 21), stellinum (fig. 22.), truncatum (fig. 23—24), as well as in the Closteria (Pl. V.), I have seen, in the very moment when the animalcule was dying under violent galvanic strokes, the coat falling off from the cuirass, and contracting itself partly. I have already said that I shall call naked the animalcules of this series, viz. the Euastra, Pediastra and Stauridia (Pl. III), the Scenodesmi (Pl. IV. fig. 49—53), the Sphaerozosmi (fig. 39), the Ophiothrix (fig. 83—84), the Sphaerodesmi (fig. 86-90), and the Oscillatoriae (fig. 71—81.). All these genera stand at the lowest degree of the animal scale, and give but weak signs of life.
