NOTES ON RETICULARIAN RHIZOPODA, 33 
so as to correspond with Dr. Carpenter’s sub-order Per- 
forata ; but, as has been before stated, the term does not 
refer to general shell-perforation but to the existence of 
stoloniferous orifices, and in this sense it is equally true of 
all polythalamous forms whether otherwise “ perforate ”’ or 
“imperforate.” Nor is there much violence to d’Orbigny’s 
original idea in accepting the orifice of Lagena, or analo- 
gous types, as a “ foramen,” though, in the absence of a 
succession of chambers, it serves only for the passage of 
pseudopodia. On these grounds, therefore, either the term 
Foraminifera, derived from the shell or other investment, or 
Reticularia, suggested by the distinctive character of the 
sarcode-body, is a sufficiently accurate designation for the 
group. 
The Foraminiferes, treated as an Order of Céphalopodes, 
were divided in the ‘Tableau Méthodique’ (1826) into five 
families, based upon the mode in which the segments were 
combined to form the polythalamous shell. After the dis- 
covery of monothalamous forms like Orbulina and Lagena, 
and the recognition of cyclical types such as Orbitolites, two 
new families were constituted for their reception. In the 
meantime, however, the researches of Dujardin had made 
known the true nature of the organization of the Rhizopoda, 
and had necessitated the removal of the group to a lower 
position in the zoological scale. Hence in d’Orbigny’s later 
works, the Foraminifcres constitute the 4th Class of Zoo- 
PHYTES (2nd Division, “ Zocphytes Globuleuz,”’ placed 
between Polypiers and Infusoires), and are divided into 
seven orders with characters which may be briefly sum- 
marised as follows : 
Order 1. Monosticures. — Shell formed of a single 
chamber. 
Order 2. CyctosticuEs. — Shell discoidal, composed of 
concentric lines of cells, simple or multiple ; never spiral. 
Order 3. SvicHostiGuUES. — Shell formed of chambers 
joined end to end in a straight or curved line; never 
spiral. 
Order 4. HxticosticuEs.—Shell composed of chambers 
in a single series, spirally coiled. 
Order 5. Entomostieurs.—Shell composed of chambers 
arranged in two alternating series and spirally coiled. 
Order 6. Exat.osvicvrs.—Shell composed of chambers 
1 « Cours Elémentaire de Paléontologie et de Geologie Stratigraphiques,’ 
vol. ii, p. 189. Paris, 1852. 
VOL, XXI, —NEW SER. Cc 
