258 REPORT OP NATIONAL MU8EUM, 1897. 



ANALYTICAL KEY TO FAMILIES. 



Siiltkiugilom I'ltorozOA. — Body consisting of a minute mass of pi<)to])lasiii, or an 

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

 either witli or witliout a testaceous envelope or skeletal framework. 



Class Rhizopoda. — Protoplasmic hody 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 Foraminifeua. — I'soudopodia protruded as fine threads which How together 

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

 vacuoles generally indistinguishable; tests either chitinous, 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, ot sponge spicules). 



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



constriction or adhesion, never truly septate Family II. Astkokiiizid.e. 



Relatively small, usuallj'^ regular in contour, one or many chambered ; many- 

 chambered forms sometimes imperfectly septate, often labyrinthic : 



Family III. Lituolide. 

 Test arenaceous or calcareous. 



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

 phous Family IV. Textulakidj^. 



Test calcareous. 



Imperforate, porcellauous 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. Chilostomellice. 

 Chambers comparatively few, inliated, 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 onlj^ on the lower (apertural) 

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



Family IX. RotalidvE. 



Chaml)ers spiral or concentric; shell symmetrical, usually lenticular or dis- 



coidal Family X. Nummulinio.e. 



analy'tical key to genera. * 



Family I. Gromid.e. 

 Aperture single. 



Test large, ovate. 



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



the body of the animal Genus fAeherkuhnia. 



Mouth terminal ; test not adherent Genus Gromia. 



Test minute, ovate. 



Mouth prominent, one-sided Genus Mikroj/roinia. 



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

 Aperture at each end. 



Test hyaline, tulmhir, cylindrical, or tlattened Genus ShepheanJella. 



