RHIZOPODA — FORAMINIFERA. 83 



there exist a number of recent species which are visible to the naked 

 eye. Some species of Orbitohtes are nearly half an inch in diameter, 

 and the discs of Cycloclypeus, dredged living off the coast of Borneo, 

 are more than two inches in diameter; and among fossil forms of 

 large dimensions may be mentioned Parkeria (Carpenter), from the 

 Upper Greensand near Cambridge, which sometimes reaches to three 

 inches in length ; and Loftusia (Brady), from Persia, specimens of 

 which have been met with three inches long and one inch and a half 

 in diameter. Here also allusion may be made to the gigantic Eozoon 

 canadense, lately discovered in the Palaeozoic rocks of Canada. 



After these remarks, we may venture to give some idea of the 

 structure and classification of beings whose part in the work of 

 creation has in former times been so considerable. 



The existing Foraminifera are by no means equally distributed in 

 every ocean. Some genera belong to warm countries, others to 

 temperate and cold climates. They are much more numerous, 

 however, and much more varied in their forms, in warm than in 

 cold climates. 



And first as to their structure. We find this to consist of a soft 

 sarcodous material of the same nature as that met with among the 

 Lobosa, and in addition they possess a calcareous skeleton. There is 

 even less approach than with the Amoebae to either shape, size, or 

 number in their pseudopodial extensions — these often present them- 

 selves as marvellously attenuated threads, requiring very high powers 

 indeed of the microscope to discern them. They coalesce both readily 

 and completely with one another, while along their margins streams of 

 granules may be seen continuously passing. There is an apparent 

 absence either of "nucleus" or of a "contractile vesicle," which 

 were occasionally present among the Lobosa. By far the larger 

 number are enclosed in calcareous shells, which are perforated with 

 minute pore-like openings for the escape of the pseudopods, and 

 from the presence of which the familiar name of Foraminifera has 

 been given to the class. These pseudopodial extensions present in 

 this group a peculiar reticulated character, whence the name of 

 Reticulosa, given to it by Dr. Carpenter, whose monograph on the 

 group is a monument of patient industry and research. 



We have already said that the shells of these minute creatures 

 vary much in form. They are generally many-chambered, each 

 chamber communicating by pores in its walls. Alcide d'Orbigny, 

 to whom — until Carpenter's " Introduction to the Study of the Fora- 

 minifera" was published — we owed almost all that was kno\vn of the 

 class, has distributed it into six families, making the form of the shell 



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