CAKPENTER ON FORAMINIFERA. 199 



only that their range of variation is extremely wide, but that a large 

 number of reputed genera and species have been erected upon no better 

 foundation than that afforded by the transitory phases of types, hitherto 

 known only in their states of more advanced development.* 



But it would be very unreasonable to put aside these cases as so far 

 exceptional, that no inferences founded upon them can have any appli- 

 cation to the higher forms of animal and vegetable life. For it is only 

 in the degree of their range of variation, that Foraminifera and Proto- 

 phyta differ from Vertebrata and Phanerogamia ; and the main principle 

 which must be taken as the basis of the systematic arrangement of the 

 former groups, — that of ascertaining the range of variation by an ex- 

 tensive comparison of individual forms, — is one which finds its applica- 

 tion in every department of Natural History, and is now recognized and 

 acted on by all the most eminent botanists and zoologists. It will be 

 sufficient for me here to refer to the views recently advanced by Dr. J. 

 D. Hooker, in his introduction to the Flora of Australia ; the results of 

 his extensive experience in the comparison of the Floras of different por- 

 tions of the globe having led him to conclusions regarding the probable 

 origin of the diversities they present, with which my own deductions 

 from the study of the Foraminifera are in complete accordance. And I 

 am authorized by Mr. T. Davidson, whose profound knowledge of the 

 Brachiopoda enables him to speak as the highest authority upon all that 

 relates to that most interesting group (which, like that of Foraminifera, 

 is traceable through the entire series of fossiliferous rocks) to state that in 

 proportion to the increase of his knowledge of its modifications of type, does 

 he find reason to regard many of them as possessing so wide a range of va- 

 riation, that he feels j ustified in making a large reduction in the number 

 of specific types hitherto accounted distinct ; whilst in the same propor- 

 tion he finds himself able to trace with considerable probability the same 

 specific types through a succession of geological periods, — certain Oolitic 

 Terebratulida, for example, being the probable ancestors of existing 

 forms; and even the Lingula of the Wenlock Silurian being specifically 

 undistinguishable from the Lingula anatena of our present seas. 



The following are the general propositions, which it appears to me 

 justifiable to base on the researches of which I now give a resume : — 



I. The range of variation is so great among Foraminifera, as to 

 include not merely the differential characters which systematists pro- 

 ceeding upon the ordinary methods have accounted specific, but also 

 those upon which the greater part of the genera of this group have been 

 founded, and even in some instances those of its orders. 



II. The ordinary notion of species, -as assemblages of individuals 

 marked out from each other by definite characters that have been gene- 

 tically transmitted from original prototypes similarly distinguished, is 



* See especially on this subject the valuable researches of Dr. J. Braxton Hicks, " On 

 the Development of the Gonidia of Lichens, in relation to the Unicellular Algse," in Quart. 

 Journ. of Micr. Science, October, 1860, and January, 1861. 



