104 



The motion of the animalcules is seldom per- 

 formed by the vesicular feet. The Frmtuliae and 

 Naviculae swim by a slow motion of the whole body 5 

 the Cosmaria and Euastra, by floating 5 the Diatomeae, 

 by moving every one of their limbs; and the Oscil- 

 latoriae by a vermicular creeping , similar to the 

 motion of earth- worms. Ophiothrix derives its name 

 from the serpentine and spiral motion, and from the 

 quickness of this animalcule, comparatively superior 

 to that of all the creatures of this series. 



The Sphaerodesmi (fig. 85 87.) roll themselves 

 by a floating motion, and rise by a spiral one, by 

 means of which, though slowly, these animalcules 

 ascend from the bottom to the surface of the water, 

 and go down again. 



The act of creeping, peculiar to several Oscil- 

 latoriae seems to be performed by pressure upon 

 neighbouring filaments or other parts. Some of these 

 animalcules are always seen creeping in company 

 under the microscope. 



The Osdllatoria subulata (fig. 71 72), standing 

 uprigh f , cannot creep with the whole body, but that 

 remarkable creature seems to be constantly employed 

 to its own propagation, considering that the coat of 

 the mother opens itself again, as well as the still 

 younger one (c. d. e.). This last filament in the 

 place where it abandons the opening of the coat, is 

 articulated , as well as the coloured content of the 

 maternal filament (d.). These articular nodes are 

 separated by filiform intervals and represent a rosary, 



