496 8CI1
queetiOD, with the abiindaDt and so long enig- matic Cordaites. This nocient plant was for- merly regarde (BiDBBn.],U«r:ooUu.Csp«Bah«mui,Bpllibiir(<in. T.GInkgi t. OlDkgo (S>U«burl>) ndlwiliildH. Ungir: Pert Onion b«d>. mIoccQe, Gmmluid. 10. Qlnkgo bllobi. L. ; Uvltig, Wuhlngi
kindly drawn for me by Ensign Everett Hay- den, U. S, navy, have been selected with a view to illustrating the phylogeny of the genus Ginkgo: and they are numbered, and as nearly as practicable arranged upon the plate, in the order of supposed development, Tfom the true Cordaites to the living Ginkgo biloba ; this being also, as will be observed, substantially the ciironological order of their appearance.
The broad leaves of some species of Coidai- tes, though more or less elongated or ellijitical in shape, possess a nervation strikingly similar to that of the later ginkgo-liku forms ; while the familiar ft-uits so abundant in the coal- measures, and which are now known to be those of Cordaites, resemble in an equally
��3. FifgiDonbyUum [NoegaenibU) OBbefUiuin (U«il. • .1, Bapcna: PermUn, H^noTi. 4. Va\tn (Jesiij.nuiU] IIOo- ir: oojIU', Slberin (iMtonil by BmtJ. 6. UlBk|n diBlMW ijatiil*. n.ap.: Lununtv, Pidotof Bocki,WyoniliiaT«rrit(M. VelLownoDe. 9. Ginkgo (Sadibaria) idlaDIolda, tiDMrr
- . All IbD Itgiin* are reduced onr-b>if. '
��takee have not been without their uses. It if the peculiarity of science that in its very erron knowledge is extended. The theory thiit Cor- daites was cycadnecons was not wholly Tklte ; the suggestion that it might be monoootyledo- nous contained a ' soul of tmth ; ' and the prca- ent opinion that it was coniferous is. I vtntun to assert, not wholly true. The truth liea in the midst of ail these opinions. It seems to be this : there were no true paleozoic CycadaraMt monocotyledons, nor Coniferae ; but Cordaitea was the prototype of ihcm all. It was in the Trias, whose flora is unfortunately tbe leas^ known of all the formations in ]mat time, liiat all these definite types of vegetation were difr ferentinted from this corapreliensive type, — ;- the Cycadaceac through their Macropteryigjurat.
��i
��i
�� �
