of Foraminiferal Structure. 169 



Again, at p. 470 of Dr. Carpenter's work ' The Micro- 

 scope,' referring to the Reticularia, he continues : — " There 

 is, moreover, a negative character of much importance which 

 is naturally associated with the absence of differentiation, 

 namely the deficiency of the ' nucleus ' and of the ' contractile 

 vesicle,' that present themselves alike in the Radiolaria and 

 the Lobosa. It is by animals belonging to tliis order that 

 those very remarkable minute shells are formed which are 

 known as Foraminifera. In Gromia^ however, we have an 

 example of a Hhizopod which very characteristically exhibits 

 the Reticularian type in the disposition of its pseudopodia, 

 but which Dr. Wallich was the first to point out possesses 

 both a nucleus and contractile vesicle, thus showing a 

 transition to the higher orders "I That is to say (at least if 

 there is any meaning in words) that the presence of the very 

 organs in Oromia^ the absence of which he had in the same 

 page declared to be " a negative character of much importancey 

 naturally associated with the absence of differentiation " merely 

 shows that it is a transitional form between the very lowest 

 and the very highest of the whole series of Rhizopods ! 



But Dr. Carpenter's extreme reluctance to relinquish his 

 published opinions even when they are demonstrated to be 

 untenable is only on a par with the vehemence with which 

 he is in the habit of enforcing his evidence when he has a 

 theory to support. Referring to M. d'Orbigny (Intr. Study 

 Forara. p. 63), he says : — " By M. d'Orbigny the family 

 Gromida was altogether ignored, no member of it having 

 been known when he first applied himself to the study of the 

 Foraminifera, and no mention having been made in his sub- 

 sequent writings, even of the typical genus Gromia described 

 by M. Dujardin in 1835, notwithstanding the clear demon- 

 stration given by that admirable observer of its close relation- 

 ship to Miliolay ..." Between the ' test ' of Gromia and that 

 of Arcella, indeed, there is little difference ; but between the 

 animals ivhich form and inhabit these 'tests' respectively, the 

 difference is as wide as any known to exist in the whole 

 Rhizopod series "! 



Lastly, as it is with the Reticularia of Dr. Carpenter, so 

 must it be with the Radiolaria. Both of these ordinal desig- 

 nations presuppose the existence of characters on which not 

 the slightest reliance can be placed ; whilst they serve 

 effectually to mask, if not entirely to supersede, those truly 

 important characters by means of which the gradational 

 advance from the most simple to the most complex type of 

 Rhizopod structure can at a glance be recognized. Indeed, 

 either ordinal name m<ay with equal aptitude be applied to the 



Ann. & Mag. N. Hist. Ser. 4. Vol. xix. 12 



