INFUSORIAL ANIMALCULES. 



37 



Fig. 45. 



XANTHIDIA. The Xanthidia belong to the Desmidiacse, one of the simplest 

 species of the Protophy tes ; it is enclosed Fir . 45 j. F j g . 43. 



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 of the 

 body which was once supposed to consist 

 of eggs. The Xanthidia exist both in a 

 living and fossil state, and are found abun- 

 dantly in flint, as will be shown hereafter. 

 They exist singly, in pairs, and in groups 

 of four, and increase by self-division. 

 Two figures of living Xanthidia are dis- 

 played in figures 44 and 45. Figure 44 is 

 a drawing of a forked Xanthidia, found by 

 Dr. Bailey in a pond near West Point : its 

 shell is green and of oval form, and its 

 natural length is one-two hundred and 

 eighty-eighth of an inch. 



Figure 45 is a different species, and rep- 

 resents a spinous Xanthidium, obtained by Dr. Mantell from a 

 Fig. 44. pond in Clapham : it is of the same size as the 



preceding specimen, and is likewise of a beautiful 



deep-green hue. 



POLYGASTRIO ANIMALCULES. 



THE PROTEUS. In figures 46, 47, and 48, a 

 most remarkable animalcule is exhibited, which varies in size from 

 one-one hundred and fortieth to one-seventieth of an inch in length. 

 It appears under the microscope as a pale-yellow mass of jelly- 

 like matter, and is endued with the power of changing its shape to a very extraor- 

 dinary degree, as is obvious from the inspection of the figures. From this cir- 

 cumstance it is termed the Proteus, the name of the wondrous sea-god, who 

 could assume, at will, every 



form, turning himself into Fig- 46. Fig. 47. 



animals, trees, fire, and 

 water, according to the 

 fables of the classic poets. 



The Proteus can hardly be 

 said to possess any original 

 shape ; for it is capable 

 of relaxing itself in one 

 place, and contracting in 

 others ; and of pushing out 

 from every part of its body 

 long arms and feelers (a a 

 , &c.), which are its organs 

 of motion, to the number 

 of ten or twelve at one 

 time. These members the 



