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32 MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH SIKKIM. 



C. circinaUs, and Thunberg's C. revoliita, both of which are singularly inapplicable. 

 Indeed the close imbrication of the fronds in the bud of Cycads renders all but im^ 

 possible a gyrate vernation, which, for my part, I should have as soon looked for in the 

 choicest of a florist's roses or camellias. The vernation and other characters of a few 

 Cycads are shown in Plate XII. 



The Ophioglossacese have more characters in common with Cycas than the Poly, 

 podiaceae, e. g. the straight vernation, the distribution of the sporangia on the margim 

 of a spicate branch, as in Ophioglossum, or in glomerate tufts, as in HelminthostJhyg 

 In the latter and perhaps most higldy organized genus of the OphioglossaccEe we have 

 the nearest approach to Cycas in the stem-structure. This stem consists of 'a central 

 column of parenchyma, surrounded by compact vascular lamina, a thin layer of 

 elongated thm-sided cambioid tissue, merging into the main parenchymatous mass 

 which IS agam enveloped in a thin rind, and thus much resembling the developing 

 apex or young frondless shoots of Cycas, with this diiference, that while the 



fronds are 



pient 



as 



ssiyely enveloped by the sheathing hases of their cycUeal predecessors 



Palms, those of Cycads have an independent origin Such 



r 



some of the 



pomts of approx^ation between Adder's-tongues and Cycas, i. e. before the latter hv 

 as uxned their h,gher and eharaeteristic structure. These relations, however are" 

 nmch theoretic interest as showing retrogressively a converging tendency from the 

 higher to the lower grades of structure. So lenaency irom tte 



In concluding this part of my commvmioation, I hav 



ery great pleasure in acknow 



ledging my deep indebtedness to Br T A,irpr«n. "•' .^'-''"l"^'""^^ "» acKnow- 

 Gardens here, who has ever been as rL^^^ !^ T' 'T™*'^'''^-' .^'^^ ^°t-- 



ready to afford me the necessary faciUties for the 



examination of the tree fevna «f «;«,- • i, • "^-c»oaij. lacmties tor tlie 



placing in my han^ ^^IZlH^r '^ *'^« ^^^ ^--*^' -^ also for Icindly 



Description of the Species 



w 



Ctathea, Sm. 



Sori on a vein, or in tlie axil of the f k* 



Involucre globose, inferior, coverinrttf 1 T ™°' ^f'^'""' "^'^^ted^ g'obose or elongated, 



forming a n.o. o. less ^.r^^Zl^ :^l r^ ™^ ""^''"^ " '""^ '""'"^'' """ 

 or subtropical. Stipes often aeuleated FronL '»=^gm.-Arborescent. tropical 



(Syn. Fil. „. ,«. °"''^"=''- ^'^ds simple or pinnate, or deconipoundly pinnate. 



1- C. SPINULOSA Will ^/* 1 



■ fronds glabrous, ' J^l'' ZtZl "* f-S^^ -Seated, often dark purple- 



««r.nl„.r ....-xu '"P;*^' swttaccid ; ptnnulea obloncr. ap,„v,;„„t„ . , , ^ ^ . 



(Syn. Fil. p. 16.) 



This 



serrulate, with small bullate scuIp. rZ ti, . , °' ^'''''^"late ; lobes acute, 



to the costules ; involucre g bos 17 tWn ? ''''^'^*' '' ''" ^f--' «1- 



irregularly. (Sy„. M. p. 23 Vll C^ -«-t»™"«. fragile, soon breaking 



% El. vi. p. 25 ; Moo Js Ind m'' 273 Lh ^l '"^ " ''"'''■ ^''' = H-"^- 



and ■■ pug.hoek " of the Lepchas ' ^^ ^''^ P' ^^' *' ^^O « Pauhyum 



i^epcbas, indigenous to their own tropical yalleyl and 



JJ 



