XV111 EXPLANATIONS OF THE PLATES. 



PLATE XV. (p. 483). 



VARIOUS FORMS OF FORAMINIFERA (Original). 



Fig. 1. Cornuspira. 



2. Spiroloculina. 



3. Triloculina. 



4. Biloculina. 



5. Peneroplis. 



6. (h*biculina (cyclical form). 



7. Orbiculina (young), 



8. Orbiculina (spiral form). 



9. Lagena. 

 10. Nodosaria. 



Fig. 11. Cristellaria. 



12. Globigerina. 



13. Polymorphina. 



14. Textularia. 



15. Discorbina. 



16. Polystomella. 



17. Planorbulina. 



18. Rotalia. 



19. Nonionina. 



PLATE XVI. (p. 509). 



VARIOUS FORMS OF FORAMINIFERA (Original). 



Fig. 1. Cycloclypeus, showing external surface, and vertical and hori- 

 zontal sections. 



2. Operculina, laid open to show its internal structure : — a, Marginal 

 cord, seen in cross section at a' ; b, b, external walls of the Chambers ; 

 c, c, cavities of the Chambers ; c' c', their Alar prolongations ; d, d, Septa, 

 divided at d' d' and at d", so as to lay open the Interseptal Canals, the 

 general distribution of which is seen in the septa e, e ; the lines radiating 

 from e, e, point to the secondary pores ; g, g, non-tubular columns. 



3. Calcarina, laid open to show its internal structure : — a, Chambered 

 portion ; b, Intermediate skeleton ; c, one of the Radiating prolongations 

 proceeding from it, with extensions of the Canal-system. 



PLATE XVII. (p. 518). 



STRUCTURE OF EOZOON CANADENSE (Original). 



Fig. 1. Portion of its Calcareous Shell, as it would appear if the Ser- 

 pentine that fills its chambers could be dissolved away : — a 1 , a 1 , Chambers 

 of lower storey, opening into each other at a, a, but occasionally separated 

 by a septum b, b ; a 2 , a 2 , Chambers of upper storey ; b, b, proper Walls 

 of the Chambers, formed of a finely-tubular or Nummuline substance; 

 c, c, Intermediate Skeleton, occasionally traversed by large Stolon- 

 passages, d, connecting the chambers of different storeys, and penetrated 

 by the arborescent systems of Canals, e, e, e. 



2. Decalcified portion, showing the Serpentinous Internal Cast of the 

 Chambers, Canals, and Tubuli of the original ; presenting an exact model 

 of the Animal-substance which originally filled them. 



PLATE XVIII. (p. 523). 

 various forms of polycystina (after Ehrenberg). 



Fig. 1. Podocyrtis ScJiomburgkii. 



2. Rhopalocanium omatum. 



3. Haliomma hystrix. 



4. Ptcrocanium, with animal. 



