Astasiaea.] THE INFUSORIA. 161 



feeble, renders it probable that the organ is a single 

 filiform proboscis. The red visual point is indicative of 

 a system of sensation, and the numerous transparent 

 vesicles within the body denote one of nutrition. The 

 creatures are parasitical upon Entomostracis and Ro- 

 tatoria. 



138. Colacium(?) vesiculosum. The bladder-shaped 

 Colacium. — Body of a spindle-shaped oval form, but vari- 

 able, with the pedicle very short, and seldom ramified ; 

 colour, a sparkling green, with distinct internal vesicles. 

 Ehrenberg says, " I have again sought in vain for the red 

 eye (May 23, 1835), but cannot be satisfied of its non- 

 existence, as it is undoubtedly present in the other species, 

 and investigation is sometimes unproductive, on account 

 of subordinate circumstances. I have likewise failed in 

 seeing very satisfactorily the vibratory organ, notwith- 

 standing its action is evident enough." In plate ii., fiff. 80 

 represents a portion of the back shield of the Cyclops 

 quadricornis (see Microscopic Cabinet, plate ix.), with six 

 of these creatures attached to it ; one appears double, 

 longitudinal self- division having just taken place. Found 

 upon Entomostraceans. Length l-860th. 



139. Colacium stentorinum. The trumpet-shaped Cola- 

 cium. — Body expansible and variable, somewhat cylindrical 

 in form, anterior expanded into a cone or funnel- sh ape ; 

 colour, a beautiful green ; vesicles indistinct, pedicle often 

 ramified. Found upon Entomostraceans and Polyarthra 

 trigla. Length 1-1 150th. 



Genus XXXVIL Distigm a. The double-eyed Astasiaea. 

 — The characteristics of this genus are the creatures being 

 possessed of two eyes, and a freedom of motion. Loco- 

 motive organs have not been hitherto discovered, and the 



