Ixxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



of the animal portion as well as of the shelly covering of these minute, 

 often microscopical, bodies, he disproved the earlier notion of their 

 alliance to the Cephalopods, which he had himself at first adopted, 

 and proposed a general classification of the Foraminifera, founded 

 upon the form of their shells, placing them amongst the Kadiata, close 

 to the Polypes. In this great and important inquiry he described 

 and figured 118 new species from the Island of Cuba and from the 

 Antilles, and afterwards 43 species from the Canaries, of which 33 

 were peculiar to those islands. Nor was it to living Foraminifera 

 that he confined his attention, as he described and figured 54 species 

 from the white chalk of the Paris basin, all, with the exception of 

 three or four, new, and then again those which had been discovered 

 by M. von Hauer in Austria, ending by the following statement of the 

 geological distribution of Foraminifera : — 



Genera. Species. 



Palaeozoic strata 1 1 



Jurassic strata 5 20 



Cretaceous strata 34 280 



Tertiary strata 56 450 



Existing epoch 68 1000 



So that it would appear that the genera and species were few in 

 number and simple in structure at first, and increased both in num- 

 ber and complexity of structure from formation to formation, until 

 they had obtained their maximum of development in the present 

 seas. M. D'Orbigny even considered that this gradual advancement 

 from simple to compound was more distinctly manifested in these 

 minute beings than in any others, and that they are in consequence 

 the best fitted for determining with precision the relative ages of 

 geological strata. The following ten living genera, Ghromia, Mimu- 

 lina, Conulina, Vertebralina, Caudenia, Pavonina, JRobertina, Cassi- 

 dulina, Unihculina, and Cruciloculina, M. D'Orbigny named as not 

 having been as yet discovered in a fossil state ; and he gave the 

 following view of the climatal distribution of the Foraminifera, which 

 cannot fail to be very suggestive to the palaeontologist also. Torrid 

 Zone, 375 species ; Temperate Zone, 350 ; Frigid Zone, 75 : so 

 that, as in Mollusca, the seas of hot climates are more productive of 

 species of Foraminifera than those of colder regions. 



M. D'Orbigny traces the history of these bodies from their first 

 discovery in 1731 to the present time ; and as a proof of the import- 

 ance of the office they may have played in the formation of some 

 geological strata (the houses of Paris and the pyramids of Egypt 

 being in part built of rocks composed of Foraminiferous shells), he 

 states that little more than an ounce in weight of the sand of the 

 Antilles yielded 480,000 of these shells. M. D'Orbigny concluded, 

 from his examination of the Foraminifera of the Paris basin, that 

 they had lived in a hot climate, and had not been subjected to the 

 wearing action of any current. 



In explaining the distribution of the Foraminifera of South America, 

 M> D'Orbigny points out how varied the groups are, under the in- 

 fluence even of chorographic differences, — the Foraminifera of the 



