THE PKOTOZOA (continued) 



SECTION I. THE FORAMINIFERA 1 



CLASS FOKAMINIFEKA 



Order 1. Gromiidea. 



2. Astrorhizidea. 



3. Lituolidea. 



4. Miliolidea. 



5. Textularidea. 



6. Chilostomellidea. 



7. Lagenidea. 



8. Globigerinidea. 



9. Rotalidea. 



10. Nummulitidea. 



THE Foraminifera received their name before their nature was 

 understood. The early anatomists, guided by the likeness of many 

 of their tests to the nautiloid shells of the Cephalopod Mollusca, 

 assigned them to this group, and many Foraminifera were included 

 by Linnaeus and later writers in the genus Nautilus. D'Orbigny, 

 in 1826, divided the "Cephalopoda," having chambered shells, into 

 Siphoniferes, with a more or less tubular siphon traversing the 

 series of chambers ; and Foraminiferes, in which the chambers are 

 in communication by foramina. The simple character of the organ- 

 isms which secreted these shells was first recognised (1835) by 

 Dujardin, who placed them with Amoeba, and allied fresh -water 

 forms in the group Rhizopoda. 



The limits of the group Foraminifera, as here understood, are 

 identical with those of the Reticularia, as defined by Carpenter in 

 his Introduction to the Study of the Foraminifera (8). It includes 

 those Protozoa the protoplasm of which secretes a test (or shell), and is 

 protruded in fine thread-like pscudopodia, which branch freely and 

 anastomose with one another, and present no obvious differentiation into 

 ectoplasm and endoplasm. 



The great majority of the members of the group form a well- 

 defined assemblage of organisms, clearly allied to one another, and 

 distinct from any other division of the Protozoa ; but we cannot 

 at present draw with any certainty the limits between the simpler 

 forms here included and some other simple members of the Protozoa. 



1 By J. J. Lister, M.A., F.R.S., Fellow of St. John's College, Cambridge. 



47 



