20 GUIDE TO THE FOSSIL INVEETEBKATE ANIMALS. 



Gallery X. Virgiilina (0 64, E 58, 65), and Bolivina (E 79) are 

 exhibited fossil representatives of Biilimininae ; Cassidulina 

 (Fig. 3, m, 0 41, E 81, 82) is the type of a third sub-family. 

 (6) Cheilostomellidae, calcareous, thin, and finely perforate, 

 with successive chambers in single, alternate, or triple series. 

 Allomorpliina (E 74), Gheilostomella (E 73), and Mlipsoidma 

 are Cretaceous or Tertiary fossils. (7) Lagenidae (Fig. ^,f-j), 

 hyaline and finely perforate, simple shell-wall ; starting with 

 a flask-shaped or spheroidal chamber as in Lagena (E 33-35), 

 other types are formed by the addition of chambers in 

 straight series, e.g. Nodosaria (0 1, E 36-38), or curved 

 e.g. Margimdina (0 6, 55, E 55, 57, 59, 60, 72), or spiral, 

 e.g. Cristellaria (0 14, 19, 44, 47, 82-85, E 61-63), or 

 in alternating double or triple series, e.g. Polymorphina 

 (0 23, 29, 30, 61-63, E 67-70), while in Bamidma the 

 chambers are joined by branching tubes ; all the genera 

 mentioned are widely distributed as fossils; (others are 

 O 3, 4, 26, 27, 51-54, 60, 67, E 40-54, 56, 66, 77). 

 (8) Globigerinidae, hyaline shell of a few swollen 

 chambers spirally arranged, Glohigcrina (Fig. 3 k, 0 17, 

 76, E 91 ; others are 0 43, 65, E 71, 92, 95). (9) Rota- 

 liidae (Fig. 3, o, p), hyaline shell typically composed of 

 chambers wound spirally like a snail-shell, and either free 

 or attached ; (Spirillina, E 31 ; Eotaliinae, 0 10, 12, 13, 15, 

 34-39, 42, 49, 69-75, 77-79, 89, E 83, 84, 86-90). (10) 

 Nummulitidae (Fig. 3, shell consists of a series of 



chambers coiled in one plane, and is often thickened by 

 extra layers of shell-substance connected with a system of 

 canals distinct from the ordinary communications between 

 the chambers and the perforations of the shell- wall ; among 

 important fossils are Fitsidina (E 96), Nonionina (0 11, 46, 

 86, E 94, 96), Polystomella (0 45, E 93), Amphistegina 

 (0 40, 98, E 97), Operculina (0 80, 88, R 98), Heterostegina 

 (0 99, E 99, 100), Nummidites (0 87), and Orbitoides. The 

 complication of structure sometimes attained in this family 

 may be studied in an enlarged model of a Nitmmulite. 



RoTALiiDAE — 0, Eotolia, Lower Cretaceous to Becent ; j), Truncatu- 

 lina, Carboniferous to Recent. 



Nummulitidae — 7', Archaediscus, Carboniferous ; s, Polystomella, Ju- 

 rassic to Recent ; t, Amphistegina, Carboniferous, and Tertiary to 

 Recent. 



The Epoch mentioned after each genus is the oldest in which it is 

 found ; all, except Archaediscus, survive to the present. The figures 

 are variously enlarged, from 10 to 100 diameters. (From Nicholson's 

 " Palseontology," after H. B. Brady.) 



