38 



VIEWS OP THE MICROSCOPIC WORLD. 



Fig. 39. 



row, numerous curved ribs branch out towards either edge. The furrows are 

 plainly discerned in the shell ; but are detected with difficulty in the living 

 Infusoria, on account of the color of the body. So closely are the ribs placed 

 together, that no less than eight are contained within the space of one-twelve 

 hundredth of an inch Figure 38 is the representation of several living animal- 

 cules of this species, found upon a branch of conferva, which is the bright green 

 vegetable matter that floats upon stagnant waters during the spring and summer. 

 The Eunotia multiplies by self-division, and in figure 39 an individual is exhibited 



undergoing this process. The 

 separation is seen to take place 

 in the direction of the length, 

 |a and in each half we can discern 

 another line of division, (a, a; 6, 

 fi &,) just commencing. Through 

 this line, when the divided por- 

 tions have arrived at maturity, and each has become a perfectly developed 

 animalcule, another separation occurs, and thus proceeds interminably. 



XANTHIDIA OR DOUBLE-BAR ANIMALCULES. This kind of Infusoria are en- 

 closed in a transparent, single-valved shell, of a globular shape, which resists the 

 action of fire, and is studded with spines or thorns : a green mass is seen in the 

 interior that is supposed to be the eggs of the creature. The bar-animalcules 

 exist both in a living and fossil state, and are found abundantly in flint, as will 

 be shown hereafter. They exist singly, in pairs, and in groups of four, and in- 

 crease by self-division. Two figures of living Xanthidia are displayed in figures 

 40 and 41. Figure 40 is a drawing of a forked bar-animalcule, Fig 40 

 found by Dr. Bailey in a pond near West Point : its shell is 

 green and of an oval form, and its natural length is one- two hun- 

 dred and eighty-eighth of an inch. 



Fig. 41. Figure 41 is a different species, and represents 



a spinous Xanthidium, obtained by Dr. Mantell 

 from a pond in Clapham : it is of the same 

 size as the preceding specimen, and is likewise 

 of a beautiful deep green hue. 



PYXIDICULA, OR ROUND BOX-ANIMALCULES. These minute creatures have 

 Fig. 43. received their scientific name from their form pyxidicula sig- 

 nifying, in the Latin language, a little box. They are enclosed 

 in a transparent, spherical, flinty case, which is marked by a 

 circular furrow, through which it readily divides, separating into 

 two hemispheres. A group of a living species of the Pyxidi- 

 cula is delineated in figures 42, 43, and 44 : a is a view of the 

 shell at right angles to that presented at 6, and exhibits the fur- 

 row through which it separates ; and c, is one of the two hem- 

 ispheres into which the shell divides. This animalcule is of a 



THE 



Fig. 42. 



Fig. 44. 



