258 REPORT OF NATIONAL MUSEUM, 1897. 



ANALYTICAL KEY TO FAMILIES. 



Subkingdom PROTOZOA. Body consisting of a minute mass of protoplasm, or an 

 aggregation of such masses, without differentiation of parts into organs or tissues, 

 either with or without a testaceous envelope or skeletal framework. 



Class RHIZOPODA. Protoplasmic body capable of protruding any portion of its 

 substance in the shape of lobes, bands, or threads, for the purpose of locomotion or 

 the prehension of food ; generally more or less completely inclosed in a testaceous 

 envelope; nucleus and contractile vesicle present or absent. 



Order FORAMINIFERA. Pseudopodia protruded as fine threads which ilow together 

 wherever they touch, forming a network of granular protoplasm; nucleus and 

 vacuoles generally indistinguishable; tests either chitmous, calcareous, or of agglu- 

 tinated sand or shells, never silicious. 

 Test chitinous, sometimes encrusted with foreign bodies. 



Aperture at one or both extremities Family I. GROMID.E. 



Test arenaceous (composed of mud, sand, shells, or sponge spicules). 



Relatively large, one-chambered, or sometimes imsymmetrically segmented by- 

 constriction or adhesion, never truly septate Family II. ASTRORIIIZII> K. 



Relatively small, usually regular in contour, one or many chambered ; maiiy- 

 chambered f<>rms sometimes imperfectly septate, often labyrinthic : 



Family III. LITUOLID.E. 

 Test arenaceous or calcareous. 



Segments in two or more .alternating series, or spiral or confused, often dimor- 

 phous Family IV. TEXTULARID^E. 



Test calcareous. 



Imperf orate, porcellanous Family V. MILIOLID.E. 



Perforate, hyaline. 



Chambers one, or many joined in a straight, curved, spiral, alternating, 

 or branching series ; aperture simple or radiate, terminal : 



Family VI. LAGENID^E. 



Chambers more or less embracing, following each other from the same end, 

 or alternately at either end, or in cycles of three : 



Family VII. CHILOSTOMELLID.E. 

 Chambers comparatively few, inflated, spirally arranged; apertures single 



or multiple, conspicuous Family VIII. GLOBIGERINID.E. 



Chambers typically spiral and rotaliform all the segments visible on the 

 upper side, those of the last convolution only on the lower (apertural) 

 side. Aberrant forms evolute, outspread, acervuliue, or irregular: 



Family IX. ROTALID^. 



Chambers spiral or concentric; shell symmetrical, usually lenticular or dis- 

 coidal Family X. NUMMULINID^E. 



ANALYTICAL KEY TO GENERA. 



Family I. GROMIIKK. 

 Aperture single. 



Test large, ovate. 



Mouth central, in a depression at the broad end ; test closely adherent to 



the body of the animal Genus LCeberkuhnia. 



Mouth terminal ; test not adherent Genus Gromia. 



Test minute, ovate. 



Mouth prominent, one-sided Genus Mikroyromia. 



Test composed largely of foreign bodies (diatoms, etc.).. .Genus Diaphoropodon. 

 Aperture at each end. 



Test hyaline, tubular, cylindrical, or flattened Genus Shepheardella. 



