INDEX 



Pseudosteles, 193. 



Psilotaceae, 398, 408. 



Psilotttm, 88 (Fig. 45) ; sporangiophore, 



147 ; spore-producing members of, 416 



(Fig. 232); anatomy of, 418 (Fig. 233); 



408, 412 (Fig. 229). 

 Pteridophyta, 288 ; balance of alternating 



generations, 36. 



Pteridosperms, their discovery, 496. 

 PtcHs, phyletic position of, 655 (Fig. 354) ; 



elata, 616 (Fig. 342) ; heterophylla, 632. 

 Pteropsida, 486. 

 Ptychocarpiis, 511, 520 (Fig. 288); unitus, 



151 (Fig. 84). 



Rachiopteris Oldhamia, 501. 



Radial construction, 201, 252. 



Radula, 264 (Fig. 125). 



Recapitulation, theory of, 173; applicable 



within limits, 185 ; exceptions to its 



applications, 159, 636, 660. 

 Receptacle of sorus, 634 ; not a result of 



" metamorphosis," 635. 

 Red Seaweeds, 67. 

 Reduction, 233, 253 ; its prevalence in 



phyletic speculation, 235; of leaf, 139; 



in moss-sporogonia, 238 ; in Ophioderma, 



241 ; follows on seed-habit, 717 ; of chro- 

 mosomes, 50 (Fig. 32) ; phyletic delay 



in, 77. 



Reduction-series, synthetic necessity of, 482. 

 Rhi~ophora, 96, 142 (Fig. 72). 

 Rhizophores, of Selaginella, 219. 

 Rhopalodia, 71 (Fig. 41). 

 Ricda, 33, 34 (Fig. 17) ; absence of polarity, 



203; archegonium of, 257 (Fig. 118). 

 Ricciocarpus, 34 (Figs. 18, i8A) ; sporo- 



gonium of, 257 (Figs. 119, 120). 

 Riella, 263. 

 Root of embryo, variable in time and place 



of origin, 671, 672; origin of, 216; 



exogenous, 219; capless, 219. 

 Root-apex of Osmundaceae, 649 (Fig. 351). 

 Rootless sporophytes, 218. 

 Roots, "free-living," 183. 

 Root-structure in Ophioglossaceae, 458 (Fig. 



256), 489. 



Sahinia, 176, 610. 



Salviniaceae, 610 ; related to Gradatae, 611. 



Schizaea, 543 (Figs. 300, 301, 302) ; anatomy, 



549- 

 Schizaeaceae, external characters, 542; spore- 



producing members, 544 ; anatomy, 547 ; 

 segmentation of sporangium, 547 (Fig. 

 305) ; phyletic position of, 654 (Fig. 354). 

 Schizoneura, 372 (Fig. 198). 

 ' Schizostelic state, 19.?. 

 J Scolopendriiini rulgare (Fig. 93) ; apogamy, 



52, 54 (Figs. 34, 35). 

 Scolecopteris, 511 (Fig. 282), 521 (Fig. 289) ; 



polymorpha, 522 (Fig. 289). 

 Secondary thickening, 690 ; in Lepidoden- 

 dron, 334 ; in Ophioglossaceae, 488. 



Seed-habit, 703, 716; often leads to re- 

 duction, 705. 



Seed-plants, balance of alternating genera- 

 tions, 43. 



Segmentation, 176; of embryo, 179; of 

 zygote in Lycopods, 345. 



Selaginella, origin of sporangium, 146 (Fig. 

 74); symmetry of, 211. 



Selaginalla apus, microsporangium of, 39 

 (Fig. 23); megasporangium of, 40 (Fig. 

 24) ; microspore of, 40 (Figs. 25, 26). 



Selaginella sanguinolenta, 299 ; Martensii, 

 299; apus, 317; rupestris, 317; helvetica, 

 316; Wallichii, 316; Kraussiana, 316; 

 inaequalifolia, 334 ; Willdonovii, 334 ; 

 laevigata, 334; spinulosa, 299 (Fig. 51); 

 basal knot of, 220 (Fig. 113); general 

 morphology of, 300 (Figs. 148, 149) ; 

 sporangia of, 316 (Figs. 163, 164); anatomy 

 of, 332 (Fig. 173) ; embryology of, 356 

 (Fig. 190). 



" Selago" condition, 164; in Lycopods, 

 164 ; in Isoetes, 165 ; in Psilotaceae, 165 ; 

 in Ophioglossaceae, 166 ; in Ferns, 167. 



Senftenbergia, 546 (Fig. 303) ; Ophioder- 

 matica, $22 (Fig. 289). 



Septa, origin of, 97, no. 



Septum in Tmesipteris, 411, 415. 



Series of progression, 10 ; of reduction, 10. 



Sexual cycle, 75. 



Sexuality, a constantly recurring feature, 9. 



Sigillaria, stelar structure, 231 ; fructifi- 

 cations of, 325 ; elongata, 337 ; elegans, 

 337 ; Menardi, 337 ; spinulosa, 337. 



Sigillariostrobus Crepini, 325. 



Simplices, 117, 497, 498, 634. 



Small-leaved types primitive, 139. 



Solenostelar structure, of Gleichenia, 562 

 ( Fi g- 313); of Matonia, 569 (Fig. 319); 

 of Loxsoina, 573 (Fig. 321) ; of Dcnu- 

 staedtiinae, 600 (Fig. 333) ; of Pteris, 616 

 (Fig. 342). 



