12 



THE AMERICAN MONTHLY 



[January, 



Pseudopodal opening terminal. 

 The plasma consists of two differ- 

 ent parts — a posterior homogeneous 

 portion with a simple nucleus, and 

 an anterior, granulous portion ; con- 

 tractile vacuoles in both. Pseudo- 

 podia homogeneous, branched, not 

 anastomosing, 



E. Ampullacea, H. Carapace 

 flask-shaped, plates in 24 rows ; 

 aperture with 12 notched teeth, 

 0-OY L, 0.04—0.05 d. 



E. Alveolata^ T)uj. Carapace 

 ovoid ; plates in 8 rows ; aperture 

 with 8 fine teeth, 0.08—0.11, half 

 as broad. Not rare. 



E. Glohosa, Carter. Shell spher- 

 ical, with small, neck-like carved 

 appendage. Plates often separated 

 by bands. 



5. Gen. Gyphoderia, Schlum. 

 Carapace elongated, retort-shaped, 

 the neck-like extension obliquely 

 cut off by the oval, pseudopodal 

 aperture ; very finely marked with 

 regular six-cornered projections. 



The plasma consists of two simi- 

 lar parts, the anterior contains nu- 

 merous contractile vesicles, the pos- 

 terior a nucleus. Pseudopodia nu- 

 merous, homogeneous, branched, 

 not anastomosing, C. Margaritacea. 

 Sch. {Lagynis haltica^ Schultze, 

 Euglypha margaritacea, Wallich.) 

 L. 0.125 — 0.2. In ditches, especially 

 in peaty soil. 



6. Gen. Trinema, Duj. {Diffiugia, 

 Ehr.) Carapace elongated, egg- 

 shaped, turgid behind, structure- i 



II. FAMILY 



less, hard. Aperture lateral, oblique 

 to the axis, with borders bent in- 

 wards. The plasma consists of 

 two unlike parts ; the posterior is 

 homogeneous and contains the nu- 

 cleus with a nucleolus, the anterior 

 is granulated. There are three con- 

 tractile vacuoles, about one-third the 

 length from the anterior end. Pseu- 

 dopodia pointed, filamentous, not 

 anastomosing. 



T. acinus, Duj. {Difflugia en- 

 chiles, Ehr.) f3.031, half as broad. In 

 fresh and old turfy water, not rare. 



7. Gen. Groinia, Duj. Carapace 

 spherical, soft, membraneous, yel- 

 lowish-brown, with a small, round 

 opening. Pseudopodia long, fila- 

 mentous, branched, anastomosing. 



G. Jluviatilis, Duj. Gr. up to 

 0.25 d. In stagnant water, with 

 plants, sometimes abundant. 



8. Gen. Pleu7'ojphrys, CI. and L. 

 Carapace irregularly oval, formed 

 by the union of siliceous particles, 

 brownish. Pseudopodia very fine, 

 branched, anastomosing, carrying 

 granules. 



P. sphfarica, CI. and L. 1. 0.02-0.1. 



9. Gen. Clathrulina, Cien. Carapa- 

 ce spherical, fenestrated, on a stalk ; 

 colorless, later brown. Plasma 

 with numerous contractile vesicles, 

 and central nucleus with nucleolus. 

 Pseudopodia numerous, branched 

 and anastomosing, carrying granules. 

 C. elegans, Cien. Test, 0.06 d. 

 Stalk, 1 — 2 1. In ditches, among 

 algje, not common. 



AMOEBINA. 



Pseudopodia large, blunt, lip or finger-like ; plasma with nucleus and contractile 

 vesicle. 

 Body without carapace, 



pseudopodia not spread out or leaf-like, 



circular, blunt, Amoeba, 



part broad, part whip-like, Podostoma. 



pseudopodia spread out leaf-like at the end, Petalopus. 



Body with carapace, 



carapace a product of secretion, 



flexible, Pseudochlamys. 



not flexible, Arcella. 



carapace incrusted with foreign bodies, 

 without tubular prolongations, Difflugia. 



with tubular prolongations (thorns), Echinopyxsis. 



C^cJrJu^j- ^^^ 



