. Les fougères et leurs alliés [microforme] : avec présentation synoptique des descriptions des American Pteridophyta au nord du Mexique . Fougères ; Fougères ; Pteridophyta ; Fougà res¨ ; ; .  !|| 16 LES FOUGÈRES ET LEURS ALLIÉS. indusiiim couvrant un seul sore. Les veines s'étendre presque à angle droit avec la nervure centrale, sont libres, et habituellement une fourche. 46. Camptosorus.-la-Marche a des feuilles oblongues ou iiidusiate linéaire sori, qui sont éparpillés irrégulièrement et partiellement la charge sur les nervures parallèles à la nervure centrale, et en partie sur ceux qui sont obliques. Ceux qui sont près de la nervure principale, sont célibataires, celles vers la marge sont souvent env

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. Our native ferns and their allies [microform] : with synoptical descriptions of the American Pteridophyta north of Mexico . Ferns; Ferns; Pteridophyta; Fougères; ; . !|| 16 OUR NATIVE FERNS AND THEIR ALLIES. indusiiim covering a single sorus. The veins extend nearly at right angles to the midvein, are free, and usually forked. 46. Camptosorus.—The walking-leaf has oblong or linear iiidusiate sori, which are irregularly scattered and borne partly on veins parallel to the midvein, and partly on those that are oblique. Those near the midvein are single, those toward the margin are often approximate in pairs and often form crooked lines. The veins are everywhere copiously reticulated. 47. Phegopteris.—In this genus the sori are round and naked as in Polypodium, with which this genus is sometimes united. The sporangia spring from the back of the veins in- stead of the apex, as in the latter genus, and the veins are free except in the § Goniopteris, in which they nre more or less united. 48. Aspidium is largely represented in our limits by two well-marked sections, which are sometimes regarded as distinct genera, and two others with characters scarcely less distinct, containing each a single species. In all the sori are roundish, and borne on the back of the veins or rarely at their apex. In § Nephrodium the indusium is cordato-reni- form or orbicular with a narrow sinus. This at first covers the sorus and is attached by its mar. gin, but later bursts away at the margin but re- mains attached at the sinus. In some species in this section the indusium becomes shrivelled ^ , ^ before the fruit matures, and in this condition Fig. 8. —Under ... , , . , . side of a ferule st'ff-might be mistaken for a ncn-indusiate species ment of Asjiiih'uin /r'' q //V/.r - »ias, with U ', ~^- o;- rndusium!' M'apni^ ^" ^ PoLVSTiCHUM the indusium is orbicular fied. (After Saciis.) and peltate, being fixed by the centre ; the veins are free, as in ^ Nephrodium. In iJ Cyrtomium

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