48 
THE VOYAGE OF H.M.S. CHALLENGER. 
Classification of the Foraminifera . 1 
It has been already stated that the French naturalist Alcide d’Orbigny was the first 
to collect the genera of Foraminifera into one zoological group. Before his day their 
external forms had been studied by a long line of eminent observers — by Plancus and 
Soldani in Italy, Ledermuller and Batsch in Germany, Linnaeus in Sweden, Fichtel and 
Moll in Austria, Walker and Montagu in England, Lamarck, Defiance and Blainville in 
France, and many others. By the earlier of these writers they were for the most part 
regarded as minute varieties of the larger animals which their shells most nearly resembled, 
and were commonly assigned to such genera as Nautilus and Serpula : by those of later 
date, who had arrived at a clearer conception of their distinctive characters, they were 
formed into independent genera, and distributed over a considerable area of the inverte- 
brata. Until they came in turn to be studied in the living condition, their true zoological 
position remained still to be determined; but meanwhile d’Orbigny did notable service 
in treating them collectively as a distinct section of the animal kingdom. 
In the “ Tableau Methodicpie,” published in 1826, the Cephalopodous Mollusca (Class 
Cephalopodes) were divided into three Orders, of which the last was devoted to the 
Foraminifera ; and the Order Foraminiferes was divided into five families, based upon the 
mode in which the segments were combined to form the polythalamous shell. After the 
discovery of monothalamous forms like Orbulina and Lcigena , 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 organisation 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, 2 the Foramini- 
feres constitute the 4th Class of Zoophytes (2nd division, “ Zoophytes globuleux,” — placed 
between Polypiers and Infusoires ), and are divided into seven Orders, with characters 
which may be briefly summarised as follows : — 
Order 1. Monostegues. — Shell formed of a single chamber. 
Order 2. Cyclostegues. — Shell discoidal, composed of concentric lines of cells, sim pie 
or multiple ; never spiral. 
Order 3. Stichostegues. — Shell formed of chambers joined end to end in a straight or 
curved line ; never spiral. 
Order 4. Helicostegues. — Shell composed of chambers in a single series, spirally coiled. 
Order 5. Entomostegues. — Shell composed of chambers arranged in two alternating 
series and spirally coiled. 
1 In this, as in other sections of the present Report, the material collected for the preliminary Notes on 
Challenger Foraminifera, published in the Quarterly Journal of Microscopial Science, 1879-1880, has been freely utilised. 
2 Cours elementaire de Paleontologie et de G4o\ogie stratigraphiques, vol. ii. p. 189. Paris, 1852. 
