102 



In the Surirella Venus (PI. I. fig. 4.) the epi- 

 dermis 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 delto'ides (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 them- 

 selves 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 (PI. 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 (PI. Ill), the 

 Scenodesmi (PI. IV. fig. 4953), the Sphaerozosmi 

 (fig. 39), the Ophiothrix (fig. 83 84), the Sphaero- 

 desmi (fig. 86 90) , and the Oscillatoriae (fig. 

 71 81.). All these genera stand at the lowest de- 

 gree of the animal scale, and give but weak signs 

 of life. 



