254 FRESH- WATER RHIZOFOUS OF NORTH AMERICA. 



rounded form it so nearly resembles an Actinophrys, that an observer for 

 the first time would be apt to take it for a colored species of the latter. 

 Attention directed to it shows that it does not always retain the spherical 

 form, but that, especially when it meets with algous filaments or similar 

 objects, it withdraws part of its pseudopods, and adapts its shape to that 

 of the object upon which it creeps. Its change is very striking when it 

 becomes greatly elongated (to 0.24 mm.), and it creeps quickly across the 

 field of view, reminding one of a caterpillar. 



Neither Cienkowski, nor Hertwig and Lesser, detected a nucleus in 

 Vampyrella, and from its absence in a marine species, Vampyrella Gompho- 

 nematis, described by Haeckel, this author has placed the genus in his 

 proposed class of Motiera* 



According to Cienkowski, the Vampyrella feeds only on the contents 

 of the cells of Spirogyra Applying itself to a filament of the alga, the 

 animal perforates a cell, and slowly transfers the contents, including the 

 chlorophyl band, to its own interior. In the same manner it may apply 

 itself to another cell, and so continue until its appetite is satisfied. 



Cienkowski remarks that the Vampyrella Spirogyrce appears to corre- 

 spond with the Amoeba lateritia of Fresenius ; and so it has seemed to me, 

 and in this view, according to the rules of zoological nomenclature, I have 

 adopted the latter specific name. 



I had repeatedly observed a bright orange-colored Heliozoan the rela- 

 tion of which for some time I did not recognize, even with the figures of 

 Vampyrella by Cienkowski, and Hertwig and Lesser, before me, and it 

 was only on reading the descriptions of the latter animal that I was led to 

 regard the former as being' the same. 



VaBEii»yreIIa lateritia, represented in figs. 10-16, pi. XLV, as I now 



suspect it to be, and as it has come under my notice, is a brick-red or 

 orange-colored Actinophrys-like creature, from 0.02857 mm. to 0.083 mm. 

 in diameter. 



The body is a spherical, finely granular mass of protoplasm, with 

 diffused oil-like molecules. For a variable depth at the periphery it is color- 

 less, but the great portion centrally is brick- or orange-red, of variable 

 intensity of hue, and is sometimes mingled with a few darker granules of the 

 same color. The mass of protoplasm may be nearly homogeneous, as seen 



* Studien iiber Moneren. Leipzig. 1870. Nachtrsige znr Monographic der Moneron, 163, Taf. vi, Fig. 1-4. 



