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PORELLA. PME 
Porella, placed by Nees and others in the same subdivision of the 
order as Radule, has really very few characters in common with it that 
are not shared also by several other genera. The only species of 
Radula that approaches it is R. Gottscheana, by the cladogenous ¢ flowers 
and the short capsule; while every other species is acranthous and has 
subcylindrical capsules three times as long as broad. Porella, however, 
differs from all Radule in the regularly pinnate and feather-like stems ; 
the azillary branches (not infra-axillary, as in Radula, but intra- 
axillary); the universal presence of underleaves, the basal angles of 
which, like the external base of the lobules, are often decurrent 
on the stem in the shape of a laciniate and crispate wing; the side leaves 
(especially on the branches) often subopposite; the bracts of the ¢@ 
spikes exactly opposite, and connate with the intervening underleat; 
the toothed or ciliated 9 bracts; the much shorter and usually less 
compressed perianth, at first constricted at the plurilaciniate mouth, and 
only becoming 2-lipped, or campanulate, by the extrusion of the fruit; 
the globose capsule, the valves of which are fissile, and in age unequally- 
lobed, but are rarely separate from each other down to the very base ; the 
smaller, shorter elaters, and the comparatively much larger spores. 
$1. Per. facie anticd 2-, posticd depressd 1-plicata, plicis carinisve sepe 
(in etate precipue) obsoletis, ore brevissime fissa, lacinulis sub 10, 
triangularibus, denticulatis spinulosisve, demum hiantia bilabiata. 
1. P. erispata. Frons mediocris lineari-lanceolata, pinnata vel subbipin- 
nata. F. conferta (ramea subopposita) ; lobo ovato-lingulato anguste 
rotundato, margine postico valde crispato basi parviauriculato, ad 
sinum 1-2-spino ; lobulo } breviore lanceolato-ligulato ; ¢. parvulis 
levibus, inferioribus mediis subduplo longioribus flavidis. F™ 
lobulis majora, cordato-linguzformia integerrima, superne recurva. 
Per. ovato-oblonga obtuse 3-carinata (antice ecarinata) ore truncato 
ciliolata. 
2. P. asperifolia. Caules sat elati, primum subdichotomi dein pinnati 
vel bipinnati. F. confertiuscula subfalcato-divergentia ; lobo ovato- 
lingulato rotundato, margine postico recurvulo basi crispulo et 
breviter 1-2-spino; lobulo 2-plo breviore ligulato, basi antica 
breviter hastato, postica longe bidentato; ¢. parvulis convexis 
seaberulis. F'* lobulis 2-plo latiora ovato-lingueformia rotundata, 
basi subdecurrente 1—4-spina. 
3. P. ptilopsis. Frons elata lanceolata bipinnata. F. magna subhorizont- 
alia vix imbricata, per paria approximata; lobo ovato-oblongo 
truncato-rotundato, margine infero recurvo; lobulo vix 2-plo 
breviore ligulato, basi externa sagittato et runcinato-ciliato; ¢. 
mediocribus subpellucidis. F'* subduplo breviora, basi utrinque 
decurrente runcinato-fimbriata. Per. alte emersa, antice obtuse 
2-plicata, postice late unicarinata, ore constricto minute spinuloso- 
denticulato, demum bilabiata. 
4, P. Miillert. Frons elata laxiuscule pinnata, pinnis longis. F. sat 
magna subdissita; lobo ovato-rhomboideo apiculato-acuto, apicem 
versus subdenticulato, basi integerrimo ; lobulo subtriplo breviore 
ligulato basi in cristam decurrente; c. parvulis. FF ligulata 
retusa, basi decurrente laciniato-cristata. 
5. P. squamulifera. Frons elata arcte pinnata angusta, ramis brevibus 
decurvulis apice parvifoliis. F. sat magna arcte imbricata, lobo 
late cordato-ovato caulem antice late transeunte, apice rotundato 
