GENUS ACTHST0SPFIJ5RIUM— ACTINOSPHSERIUM EICHHORNII. 263 



exterior layer. It contained several articles of food, among which were 

 conspicuously seen a diatom and a large rotifer. After twent) r -four hours 

 all the food was expelled except one green alga, and the animal had 

 assumed a globular form, 0.28 mm. in diameter. No rays appeared, and 

 later the animal died. 



In several instances I have observed bodies, as represented in figs. 1 1 , 

 12, which possessed the shape, size, and apparent vesicular constitution of 

 Actinosphocrium cichhomii, but they were lifeless, and the vesicles were 

 composed of structureless membrane, without a trace of interior or exterior 

 liquid protoplasm. Whether these bodies really have any relationship with 

 Actinosphserium, or whether they pertain to some other animal, I have not 

 been able to determine. Found in the same localities in which I had, at 

 an earlier season of the year, observed many active individuals of Actino- 

 sphserium, I have suspected that they might be of the nature of an exuvium, 

 discharged in some way by the latter. 



Another enigmatic body occasionally met with, as represented in figs. 

 9, 10, I have suspected to be a fragment of an Actinosphserium. In this 

 particular specimen, of which two views are given, the body consisted of a 

 globule of granular protoplasm, containing at first two vesicles, and then, 

 by union of these, a single larger vesicle, and a single pseudopodal ray 

 sustained by an axial thread. 



Another specimen, represented in fig. 8, consisted of a globule of gran- 

 ular protoplasm, proportionately more abundant than usual, together with 

 a number of included vesicles of variable sizes. From the body there pro- 

 jected four long, delicate rays, upon each of which there was a large drop 

 of protoplasm. I am uncertain whether the specimen had any relationship 

 with Actinosphserium. 



Actinosplwrium cichhomii exhibits a considerable range of size. Ordi- 

 narily, spherical individuals are from 0.166 mm. to 0.33 mm. in diameter, 

 with the rays usually of less length than the diameter of the body, and 

 commonly from 0.1 mm. to 0.2 mm. long. Oval individuals reach 0.66 

 mm. in length. 



Actinosphccrium cichhomii is found in the same kind of localities as 

 Actinophrys sol, and in association with it. Its favorite resort is quiet water 

 among duckmeat, hornwort, etc. It commonly appears nearly stationary, 

 or as if gently floated along by an imperceptible current of the water. It 



