Page:Natural History Review (1861).djvu/470

458 seems to me) on a truer perception of the value of characters than most of the classifications that have been since proposed. For Dujardin distinctly recognized the fact that Arcella and Difflugia are nothing else than testaceous Amœbans; and in separating these from those Rhizopods which are characterized by the possession of filiform, tapering, or ramifying pseudopodia, he laid the foundation of a truly natural grouping of the latter. Had he recognized the fact that his group of (testaceous) Rhizopods is related, on the one side, not less closely to Actinophrys than it is, on the other, to Amœba, and thatTrinema and Euglypha are really formed on the Actinophryan type, whilst Gromia is the representative of the Foraminiferous, he would have marked out, upon a sound basis, what appear to me to be the fundamental divisions of the class. Even in separating Miliola from the ordinary Foraminifera, he adopted a principle which I believe to be perfectly correct, though his limited acquaintance with the group misled him in the application of it; for, as I shall hereafter show, Miliola is the type of a large group of Foraminifera in which the body is inclosed by an imperforate shell, so that there is no exit for its pseudopodial extensions except by the apertural plane, in which there is sometimes (as in Miliola) a single large orifice, whilst in other cases it is replaced by a multiplicity of distinct pores. The differentiation between this group and the one in which the shell, being everywhere perforated with pores more or less fine, allows the passage of pseudopodia from every part of the surface of the body, I hold, with Dujardin, to be of essential importance.

These considerations have been altogether passed over, not only by M. D'Orbigny, who adopted Dujardin's rectification of the position of the Foraminifera in the zoological series, without in any way modifying the classification of the group which he had previously devised under the notion that the animals by which these shells are formed are minute Cephalopods, but also by Prof. Schultze, who, having applied himself to the study of the Foraminifera and their allies in the living condition, might be expected to have gained more insight into their true relations as indicated by the characters furnished by their sarcode-bodies. Yet he shows himself to be so completely under the influence of views of systematization based on the characters of the shell, and to have so little regard even to the most important structural and physiological differences anywhere presented by the animals of this class, as to associate in his family Lagynidæ —for no other reason than that they agree in the possession of a unilocular test, Arcella and Difflugia—whose animals are of the Amœban type, Trinema and Euglypha—whose animals are Actinophryan in character, Gromia—whose animal is the type of that of the imperforate-shelled Foraminifera, Squamulina—which has an imperforate calcareous shell of the Milioline type, and Ovulina—whose shell is