New Infusoria from, the United States. By Dr. A. G. Stokes. 699 
The food of this interesting form seems to be chiefly vegetable, the 
infusorian feeding greedily upon spores and diatoms, which it engulfs 
apparently by suction. The body is very soft and flexible, easily 
forcing itself through narrow places and quickly turning on its 
course by a flexure or doubling of itself. 
For the pleasure of studying it I am indebted to Dr. P. L. Hatch, 
of Minneapolis, Minn., who finds it abundantly during the summer 
months in grassy and shallow ponds, and observes that it thrives 
almost as well in standing water. He also reports that the anal 
aperture is postero-terminal. 
Strombidinopsis similis. Fig. 5. 
Body ohovate, about twice as long as broad, finely striate longitu- 
dinally ; frontal border truncate, slightly oblique, the body being 
somewhat constricted beneath it ; posterior extremity obtusely rounded ; 
a series of fine, hair-like setae outwardly directed and projecting from 
the cuticular surface immediately beneath the peristome border, their 
length about one-half that of the body; oral depression broad, 
excavate, and continued as a wide, conspicuous, ciliated, pharyngeal 
passage extending to near the centre of one lateral border of the zooid, 
a tongue-like motionless projection present on one internal lateral 
margin of the peristome border, the oral depression appearing to 
be rather deeper beneath it than elsewhere ; contractile vesicle single, 
spherical, located posteriorly ; nucleus not observed. Length of body 
1/400 in. Hab. standing pond water. 
This form remotely resembles the author’s Strombidinopsis setigera , 
and both so differ in important particulars from the typical Strombi- 
dinopsis that it may at some time be proper to relegate them to a 
new genus. The present form differs from that just referred to, in 
the general shape of the body, the presence of the apparently rigid, 
tongue-like peristomial projection, but particularly in a characteristic 
habit of producing from the mucous secretions of the cuticular surface 
a soft, shapeless, indistinct, sheath-like covering into which it retreats 
backward at the approach of danger. The frontal region is then 
somewhat contracted, the cilia and setae being projected forward, the 
animal gliding backward for only a momentary and a very imperfect 
concealment. The mucous covering is so slight that it would com- 
monly be unnoticeable but for the adhesion of minute floating 
particles and of rejected food. Its production seems to be involuntary ; 
it is at least without definite form or describahle consistence. The 
infusorian is in no way attached to this mucous formation, and may 
leave it at will. The creature at times avails itself of almost any soft 
collection of debris, beneath which it temporarily and imperfectly 
conceals itself while its ciliary currents bring to it the food morsels it 
needs. The peristomial cilia are capable of individual movement, the 
infusorian having complete control of each and all. 
3 d 2 
