R. J. L. Gupiyy — Foraminifera of Trinidad. 



249 



iinstead of doing this, develop an additional portion, segment, or cell 

 to accommodate the increased size of the body. This is incremental 

 growth as contrasted with the interstitial growth of the soft parts. 

 The idea, therefore, that a polythalamons foraminifer is a colony and 

 not a single organism is not well founded. No doubt the idea is 

 derived from the coelenterata, where separate polyps are developed 

 one from another, the whole mass of polyps nevertheless remaining 

 in union and forming what is designated as a colony. In one sense 

 perhaps every animal may be regarded as a colony. But the 

 foraminifer is not more so than a Nautilus. 



EUipsoidina 



Pleurostomella 



Textularia \ 

 Spiroplecta ) 



Milioliua 



Lao-ena 



O 



Primordial form. 

 Diagram to illustrate the Phylogeny of Nodosaria and allied forms. 



(Uvigerina 

 J Sagrina 



Linffulina 



Prondicularia 



Cristellaria 



Polymorphina 



EXPLANATION OF PLATES VIII AND IX. 



Plate VIII. 



IFiGS. l-i.~Gonatosphcera prolata. Views of different specimens of the perfect 

 adult form. 

 , , 5-7.— Specimens in which the last chamber has been broken away, leaving the 

 ridge where the wall of the last chamber was adherent to the previous 

 segment. In Fig. 7 a portion of the wall of the last chamber still 

 remains. 

 -Nodosaria alyssorum. Figs. 12, 13. — Nodosaria longiscata. 



8, 9. 



10, 11. — Nodosaria hispida. 



14, 15. — Nodosaria arundinea. 



