OF THE PROTOZOA. RHIZOPODA. 241 



RHIZOPODA. 

 A. NUDA. 



G-en. Amoeba (Noctiluca?). 



B. TESTACEA. 



I. MONOTHA LAMIA. 



Testa or shell one-chambered ; animal imdivided, having the same conformation as the shell. 



Fam. 1. Lagvnida. — A sacciform, calcareous or membranous, non-porous testa, with a large 

 opening. 

 Gen. Arcella, Difflugia, Trinema, Euglypha, Gromia, Lagynis, Ovulina, Fis- 

 sm'ina, Squamulina. 



Fam. 2. Orbulinida. — A globose, calcareous testa, finely porous throughout, without a 

 large opening. 

 Gen. Orbulina. 



Fam. 3. Cornuspirida. — A calcareous shell, convoluted like that of a Planorbis, with a 

 large opening. 

 Gen. Cornuspira. 



II. POLYTHALAMIA. 



Shell polythalamous ; the animal composed of segments, connected by commissural bands. 



1. G-roup Helicoidea. 

 The chambers disposed in a spiral. 



Fam. 4. Miljolida. — Each chamber occupies a half-spiral, which is developed either in 

 one plane or in various planes. The shell has only one large opening 

 at the extremity of the last spiral, and no pores. 

 G-en. Uniloculina, Biloculina, Miliola, Spiroloculina, Articulina, Sphee- 

 roidina, Adelosina, Fabularia. 



Fam. 5. Turbinoida. — The chambers so disposed spirally as to resemble the shell of Helix 

 or Tm-bo. The spiral is only visible on one side of the shell. Some 

 are so much elongated that the chambers are, as it were, disposed 

 alternately in two contiguous rows. The shell has a large opening 

 in the last chamber, and its sm'face is almost always finely perforated. 

 Subfam. 1 . Rotalida. — Shell flattened or conical ; chambers do not encircle each 

 other ; shell glass-like, transparent ; finely perforated. 

 Gen. Rotalia, Rosalina, Trmicatulina, Anomalina, Planorbulina, Asterigerina, 

 Calcarina, Siphonina, Planulina, Colpopleura, Porospira, Aspidospira. 

 Subfam. 2. Uvellida. — Shell in the form of a longer or shorter cluster like a bunch 

 of grapes. The chambers frequently appear to ahnost completely 

 embrace one another. Shell usually thick and coarsely perforate, 

 or solid. 

 G-eh. Globigerina, Bulimina, Uvigerina, G-uttulina, Candeina, Globulina, 

 Chrysalidina, Pyrulina, Clavulina, Polymorphina, Dimorphina, Ver- 

 neuillina, Chilostomella, Allomorphina, Ehynchospira, Strophoconus, 

 G-rammobotrys. 

 Subfam. 3. Textilarida. — Spire so much produced that the chambers form a double 

 row and alternate. 

 G-en. Gaudryna, Textilaria, Virgulina, Vulvulina, Sagrina, Bigenerina, Bo- 

 livina, Gemmulina, Cmaeolina, Clidostomum, Proroporus. 

 Subfam. 4. Cassidulinida. — Textilaridas curved once in a direction perpendicular to 

 the original spiral. 

 Gen. Ehrenbergina, Cassidulina. 



Fam. 6. Nautiloida. — The chambers so disposed spirally that the shell has a general 

 resemblance to that of an Ammonite or Nautilus. The spire is either 

 visible or, otherwise, concealed on both sides of the shell. The anterior 

 wall of the last chamber is furnished with one larger or several smaller 

 openings ; the other portion of the shell is usually finely perforated. 



Subfam. 1. CristeUarida.—^\\e\\ thick, finely perforate, colourless, transparent; 

 chambers encircling, -with a large opening at the upper angle of the 

 anterior wall of the last chamber, which corresponds in position with 

 the communicating openings between the sevei-al chambers. 

 Gen. Cristellaria, Robulina, Marginulina, Flabelliaa. 



Subfam. 2. Nonionida. — Shell thick or tliin, colourless, transparent, finely perforate ; 

 chambers either encircling (imbricate) or not. The opening is in the 



