98 DESCRIPTION OF [Polygastrica. 



division is completed. Size about 1 -2000th to l-900th ; 

 diameter of clusters, l-380th. 



Genus IV. MICROGLENA. The eye Monad. This genus 

 is essentially characterized by the species all having a minute 

 red eye-like speck, situated within the creature, at the 

 anterior part of the body. In other respects they resemble 

 true Monads, by being deficient of the projecting lips and 

 tail, and by their swimming in the direction of the long 

 axis of the body. They possess a very delicate flagelliform 

 proboscis, of simple structure. They multiply by a com- 

 plete self-division of the body. Two species only are 

 known, the one yellow, and the other green. 



We now approach to a description of living creatures, 

 whose organization, on account of their magnitude, is 

 rendered more apparent to us. The red eye -like speck, 

 the distinguishing feature of this genus, may be assumed 

 to be a rudimentary visual organ, notwithstanding nervous 

 ganglia subservient to it have not been perceived, as with 

 the still larger Infusoria, the Euglena, Rotatoria, and single- 

 eyed genus of Entomostraceans, the Daphnia. This organ, 

 together with the proboscis, its locomotive and purveying 

 instrument, the beautiful green homogenous granules seen 

 in M. monadina, which, by their shape and situation in the 

 body, leave no reasonable doubt of their being ova, and 

 the grey rolled band-like seminal gland, demonstrate that 

 these living atoms are endowed with systems of orga- 

 nization (a sensitive one too) as conformable to their par- 

 ticular uses, and as well adapted to supply the wants of 

 the creatures, as those even in the largest fish. Still are 

 we left to conjecture with respect to their possessing a 

 vascular system or not: it has never been perceived, and 



