HISTORICAL SUMMARY. 7 



The results of M. D'Orbigny's researches on Foraminifera are for the most part recorded 

 in local Faunas. Thus he furnished to the great work of Ramon de la Saj^ra upon Cuba 

 (xcii), an important article upon the Foraminifera of that island ; a similar contribution to the 

 account of the Canary Islands, by MM. Barker-Webb and Berthelot (v) ; and a description 

 of the Foraminifera of South America to his own travels in that country (lxx). So, in his 

 ' Faune de la Craie blanche de Paris' (lxxi) he described the Foraminifera of that deposit; 

 and in a subsequent work on the fossil Foraminifera of the Tertiary Basin of Vienna (lxxiii) 

 he took the opportunity afforded by the extraordinary richness of the collection he thence 

 obtained thrcutrh Baron Hauer, to give a general conspectus of the entire group as then 

 known to him, at the same time expressing his entire change of opinion in regard to the nature 

 of the animal by which the shells of the Foraminifera are formed. His latest views on the 

 general classification of Foraminifera are contained in his ' Elementary Course of Palseontology 

 and Geology' (lxxiv), wherein we find a description of all the generic types that occur fossil, 

 to which the number of such as are only known at the present epoch bears an insignificant 

 proportion. It is here that we meet for the first time with his order Cychstt'gues, which 

 includes only four genera ; — Orbifolilcs, previously ranked among corals ; Ci/clolina, instituted 

 by himself in 18;57, but previously ranked among the lUlicostegues ; with Orbilolina and 

 'Orbitoides, instituted by himself in 1847, but not previously introduced into his classification. 



The iliird period, with which our knowledge of the true nature of the Foraminifera 

 really commenced, is inagurated by the discovery, first announced by M. Dujardin to the 

 Academic des Sciences in June, 1835, of the Rhizopod type of structure (xxxiii), which was 

 followed by the demonstration of the essential identity between the ylmwba and other simple 

 fresh-water Rhizopods (described by Prof. Ehrenberg among the Polygastric Animalcules) and 

 the Crisfellaria and similar composite forms of marine Foraminifera which had been previously 

 ranked among Cephalopod Mollusks (xxxi v). The general results of M. Dujardin's observations 

 were, that the animal body consists, alike in the naked and in the testaceous Rhizopods, of a 

 mass o^sarcode, a gelatinous, somewhat granular substance, not enclosed in a distinct membrane, 

 and capable of extending itself into threads of extreme tenuity ; that there is neither mouth 

 nor digestive cavity, but that alimentary particles, received into the very substance of the 

 body, are gradually incorporated with it ; and that both the introduction of these particles 

 and the movements of locomotion are effected by means of pseudopodial prolongations of the 

 sarcode, put forth in the testaceous forms through apertures in the shell, and capable, when 

 retracted again, of coalescing with the general mass. In the case of the composite forms, he con- 

 sidered the entire animal to be made up of a series of segments which are essentially repetitions 

 one of another, each possessing an independent vitality of its own (xxxvi). He seems to have 

 continued for some time, however, in uncertainty as to the extent to which this description of 

 the animal would be applicable to all the bodies ranked by M. D'Orbigny among the Forami- 

 nifera ; as we find appended to the names of several of those described by him in the 

 ' Dictionnaire Universelle d'Histoire Naturelle' (as Nonionina, Nummulites, and Rotalia) the 

 abbreviation 3Ioll. ? as well as Foram. 



In the article 'Foraminiferes' cowir\h\xi(ii by M. D'Orbigny in 1844 to the same Dictionary 

 (lxxit), he altogether abandoned the notion of the Cephalopod affinities of the group (without 

 giving the least hint that he had ever himself entertained it), and described the structure of 



