CABPENTEB ON THE' \K"\^ ' m;\t or THE EHIZOPODA. lo7 



Ciplea on which its various forms should 1 »o classified into Orders and 

 Families; so iliai among the Writings of recent Wtfteiriatists there fe 

 a complete (listuu'onlanco as t6 the relative 1 places 1 assifeed to tli"in. 

 Having been recently led to inquire into this subject with sonic eare, 

 for the purpose of determining the relations of the Foraminifera to 

 the other members of the class, and having been encouraged to believe 

 that my results mav be deemed worthy of acceptance by other Natu- 

 ralists, I avail myself of the pages of the "Natural History Ke\ie\v"' 

 to bring them in a eoncise form under their consideration ; referring 

 to my forthcoming "Introduction to the Study of the froraminifera;'* 

 shortly to be published by the Ray Society, for a fuller exposition 

 of them. 



It is not a little singular that Dujardin, who first discovered the 

 true "idea" of the Ehizopodous type,* and to whose original account 

 little of importance has subsequently beeu added, should have so 

 limited his definition of it as actually to exclude some of what we 

 now regard as its most characteristic examples. In his " Histoire 

 Natureue des Zoophytes Infusoires" (Paris, 1841), he ranks the 

 Amibiens as the second family of his Ikfusoires, the Rhizopodcs as 

 the third, and the Act inoplir -yens as the fourth ; but he distinctly 

 states that the structure of the animal is essentially the same in the 

 first two cases, and that the Rhizopodes are differentiated from the 

 Amibiens solely by the enclosure of their bodies in a testaceous 

 envelope, varying in consistence from a simple flexible membrane to 

 a thick calcareous shell, either solid or porous. He does not, how- 

 ever, regard the differences in the texture of the envelope as equal in 

 importance to those presented by the form of the pscudopodian 

 extensions of the sarcode-body, according to which the RJiizopode.s- may 

 he divided into two sections; of which the iirst (corresponding to 

 Ehrcnberg's family An-rllina) includes only the Areelhe and J)if- 

 jlugice, whose bseu I are short, thick, and rounded at their 



extremities; whilst the second comprehends all those whose psetnlo- 

 podia are filiform and much attenuated towards their extremities. 

 This second section was subdivided by Dujardin into three tribes ; 

 the first composed of the genera Trinema, Euc/lypha, and Gromia 

 (all discovered by himself), which are distinguished from Difflurjia 

 only by the attenuation of their pseudopodia ; the second is composed 

 of the single genus MilioJa, which agrees with the ordinary Forami- 

 nifera in the possession of a calcareous shell, whilst it corresponds 

 with Gromia in having but a single large aperture from which the 

 p.-udopodia extend themselves ; and the third includes the Ilnnnini- 

 fera proper, all of which were supposed by Dujardin to be furnished 

 (like the few observed by himself) with porous shells for the i 

 pseudopodia from the general surface of the body. 



Now this arrangement, imperfect though it was, is ha-od (as it 



* "Observations sur les Ilhkopcdis ct les 1 nj'usol res ;" -in Conqjics RendftS, 

 1835, p. 333. 



