584 DE. CAEPENTEE'S EESEAECHES ON THE FOEAMINIFERA. 



than that afforded by the transitory phases of types hitherto known only in their states 

 of more advanced development*. It would be very unreasonable to put aside these 

 cases as so far exceptional that no inferences founded upon them can have any applica- 

 tion to the higher forms of Animal and Vegetable life. For it is only in the degree of 

 their range of variation, that Foraminifera and ProtopJiyta differ from Vertcbrata and 

 Phanerogarnia ; and the main principle which must be taken as the basis of the system- 

 atic arrangement of the former groups, that of ascertaining the range of variation 

 by an extensive comparison of individual forms, is one which finds its application 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 portions 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. THOMAS 

 DAVIDSON, whose extensive knowledge of the Srachiopoda enables him to speak as the 

 highest authority upon all that relates to that most interesting group (which, like the 

 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 having had so wide a range of variation, as fully to 

 justify him in making a large reduction in the number of specific types hitherto accounted 

 distinct ; whilst in the same proportion he finds himself able to trace with considerable 

 probability the same specific types through a succession of geological periods, certain 

 Oolitic and Cretaceous Terebratulidce, for example, being the probable ancestors of 

 existing forms ; and even the Lingula of the Wenlock Silurians not being distinguish- 

 able by any characters which he can re.cognize as constituting a valid specific difference 

 from the Lingula anatina of our present seas. 



261. The following are the general propositions which it appears to me justifiable to 

 base on the researches of which I have now given a resume : 



I. The range of variation is so great among Foraminifera, as to include not merely the 

 differential characters which systematists proceeding 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 genetically transmitted from original proto- 

 types similarly distinguished, is quite inapplicable to this group ; since even if the limits 



* It is among the lower Fungi that the researches of TULASNE and others have shown the greatest 

 variability to prevail ; whilst the recent inquiries of Dr. J. BBAXTON HICKB have hrought to light a most 

 unexpected relationship between the supposed Unicellular Algae and the Gonidia of Lichens. See his 

 Memoirs in the Quarterly Journal of Microscopical Science, October 1860 and January 1861. 



