The Annals and magazine of natural history; zoology, botany, and geology . e process of meta-morphism can be very distinctlytraced, and we then see in differ-ent specimens and differentvarieties a gradual passage fromtheir original figure to one orother of the various metamorphicforms of which mention has beenmade. Where large oval or cir-cular diatom-valves have formed part of the test these appear, in some of Prof. Leidys figures,to pass eventually into true circular or oval hyaline plates ofproportionately large dimensions. 1 have only space to add that the appearances described ascharacter
The Annals and magazine of natural history; zoology, botany, and geology . e process of meta-morphism can be very distinctlytraced, and we then see in differ-ent specimens and differentvarieties a gradual passage fromtheir original figure to one orother of the various metamorphicforms of which mention has beenmade. Where large oval or cir-cular diatom-valves have formed part of the test these appear, in some of Prof. Leidys figures,to pass eventually into true circular or oval hyaline plates ofproportionately large dimensions. 1 have only space to add that the appearances described ascharacterizing the metamorphic series are not confined to themitriform and pyriform varieties, though they would appear toreach their climax in them. They are likewise observablein the globular and oblique, or, as 1 have termed it, the mar-supiiform series, of which Difflugia spiralis and D. cassisare offshoots. In the former of these two the chitinous pelletsand cylinders, whether straight or bent, seem to arrive at theirmaximum of development. But, strange to say, I have never. Dr. Wallicli on the Rhizopods. 471 met with a single example anywhere in which there occurredso close an approach to distinct siliceous rods and plates asis to be seen in pi. xix. of Prof. Leidjs series. I havenevertheless met with specimens of D. cassis in which therewas a row of circular colloid disks surrounding the aperture ofthe test. Before bringing my remarks on the Difflugian Rhizopodsto a close, I must point out that, although Prof. Leidy haspaid me the compliment of adopting nearly every fact andconclusion of mine in relation to the forms he has transferredto his new genus Nehela^ the only direct reference made byhim to my previous writings on these forms is contained inthe following brief paragraph at p. 151 of his observations onthe Nebelidaj; and even here the scope of the remark he isquoting is very materially impaired by his having cut shortthe sentence at the word occur :— Dr. Wallich^ in refe
Size: 1364px × 1831px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondo, bookyear1885
