INTRODUCTION TO THE STUDY 



FORAMINIFERA. 



CHAPTER I. 



HISTORICAL SUMMARY. 



The group of Animals now generally known under the designation Foraminifera has 

 only of late received even a small measure of that attention which it is entitled to claim, no 

 less in virtue of its physiological interest, than on account of its zoological and its geological 

 importance. It is true that of the minute polythalamous shells of which the group is for the 

 most part composed, many forms have long been familiar to those Testaceologists who did not 

 limit their attention to the larger shells of ordinary Mollusks ; but the strong resemblance 

 which many of them bear to the polythalamous shells of the Nautilm, Ort/ioceras, &c., led to a 

 general belief that the former belong to animals closely allied in structure to those which pro- 

 duce the latter. Hence Foraminifera were in the first instance ranked as minute forms oi Nautili; 

 and although a larger acquaintance with their varied forms, and a more exact appreciation of 

 the differential characters of these, led to the institution of a considerable number of new 

 genera for their reception, yet their title to constitute a distinct and peculiar group was not 

 recognised until the year 1825, when it was pointed out by M. D'Orbigny that, whilst the 

 larger polythalamous shells have their septa traversed by a continuous tube or siphon, usually 

 membranous, but sometimes shelly, the chambers of these minuter forms communicate by 

 s\m^\Q foramina in the septa which divide them — a difference on which he founded his primary 

 division of the class Cephalopoda into two orders, the Sijjhonifera and the Foraminifera. 

 Although, as will presently appear, the latter o( these titles was conferred under an entire 

 misconception of the character of the organisms to which it was applied, yet it has continued 

 to be that under which they have been since most generally known, none more appropriate 

 having been yet proposed ; and there can be no doubt that M. D'Orbigny's limitation and 

 designation of the group has had a most important influence in promoting that more special 

 study which it has since received, and ofnvhich the results are found to possess an interest and 

 importance that bear no proportion to the apparent insignificance of the objects which have 

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