3fo)iach'>in.'\ 



INFUSOEIAL ANIMALCULKS. 



117 



no 3fonndina can voluntarily alter tlio shape of its body, whether 

 into a filiform, knotty, or globular figure, nor can it extend any 

 portion of it, and then contract it again. It is quite evident that 

 they all jjossess organs of locomotion, nutrition, and propagation, 

 which latter are of the hermaphrodite character. Some of them 

 have a rudimentaiy eye, but it has never been discerned that they 

 are furnished with a vascular or circulating system, which, however, 

 is not surprising, when we reflect that should they possess it (a sup- 

 position by no means to be rejected), the diameters of the tubes of 

 this system would necessarily be of such extreme minuteness as to 

 defy investigation. 



The groups and figures in Plate I., numbered I to 20, convey a 

 very fair idea of the appearance of the Monadina. None but mi- 

 croscopes of high magnifying powers can develope theii- sti-uctures ; 

 indeed, they cannot be observed accui'ately with a less amplification 

 than 500 diameters, together with considerable penetration and a 

 good definition. 



The family is distributed by Ehrenbcrg among nine genera, as 

 follow ; — 



f single Hlonas. 



Eye wanting < 



L Aggregate Uvella. 



Swimming < 



Eye present < 



r Proboscis \ Mic-o^iena 

 one or two ) Micro^iena. 



Single < 



Proboscides not i 

 more than four I 



Proboscides 

 many 



Chloraster. 



Phacelomonas. 



Aggregate Glenomorum. 



Rolling Doxococcus. 



Lips present Chilomonas. 



Tail present Bodo. 



Eeference to the classification proposed at (page 62), will show 

 that the genera comprehended by Ehrenberg, in this family Monadina, 

 as well as in Ch-yptonionadina, Volvocina and Vibrionia, are not re- 

 cognized as Infusoria, by Siebold. For so extensive an exclusion of 

 genera from the List of Infusoria, Siebold offers no distinct and clear 

 explanation, but fi-om his remarks, we may gather that the excluded 



