101 



The Cosmarium deltoides (fig. 18 19) has two 

 warty cuirasses , united on their broad surface , the 

 openings of which communicate only with the sur- 

 face uniting both animalcules. The Cosmarium bipes 

 (fig. 20) has a cuirass of the same form, and appears 

 however always split on its external surface, the 

 more so as, during fecondation, this fissure (fig. 20. 

 a. a ) opens itself. In the middle of the lines which 

 unite the two cuirasses of an animalcule , we see a 

 nearly quadrangular opening of the uniting points 5 

 which opening is the mouth. On both sides of it are 

 tw r o openings (fig. 20. b.), through which the ani- 

 malcule pushes a scarcely perceptible bladder, by 

 means of which it sticks to the inside of the glass. 

 I name therefore these openings pedal holes. 



In the Colpopella viridis (fig. 28) we see, on the 

 inferior surface of the univalve cuirass two ope- 

 nings (a), placed opposite one another, which must 

 be considered as those of the alimentary tube. 



I name coat the epidermis which surrounds entirely 

 the animalcule; and, as far as I could observe it in 

 some larger species of Nariculae, inhabitants of 

 rivers , that coat is , at the same time , the pedal 

 organ, which, under a vesicular form, passes through 

 the valvular openings, and by means of these feet 

 the animalcule adheres to the glass. 



In the cuirassed animalcules (such as the various 

 species of Surirella, Navicula, Closlerium and Cos- 

 marium'), the epidermis clothes the whole internal 

 surface of the cuirass, and lines it like a bag. 



