if
I. Dunkerron, Dr. Taylor ; Dingle Bay, Dr. Carrington; limestone
rocks near Cork and Fermoy, I. Carroll; abundant on the
walls of the bridge at Cong, Co. Galwaj'; Sillaghbraes, near
Larne, Co. Antrim, Dr. D. Moore; on sandy ground at the
North Bull, near Dublin, D. McArdle; Island of Eathlin, Co.
Antrim, 8. A. Steicart.
Found on the Continent, Asia, North and South America,
Java, Japjan, Australia, New Zealand.
Obs.—Much rarer than Preissia comnmtaia, with which it is
frequently confounded. “ Easily distinguished by the deeply
divided 4-5-fid receptacle, which is barbate beneath and at the
base of the peduncle, and by tlie sessile antheridia, whereas the
recejitacle of Preissia commidata is marked on the top with a
cruciate crest and the J jredunculate.”—Dr. Carrington.
iknother character at once makes tlie difference certain viz.,
the innermost layer of the walls of the capsule of P. conmútala
have in their cells reddish-brown spiral threads, whereas they are
absent in this species.
D escription of P late CCX.—Figs. 1-4. Fertile plants natural
size. 5. Frond, piostical view. 6. Plant with young (a J ) and
(h ¥). 7. Cross-section of pedicel X 11 (W. H. P.). 8-13. Female
receptacles. 14. Ditto, showing young capsule. 15, 16, 17. Capsule
iu different stages x ?. 18. Spores x ?. 19. Spore and
elater, more highly magnified. 20. Cross-section of male receptacle
x ? (Bischoff).
Genus 48. PREISSIA, Corda.
Preissia, Corda in Opiz Natiiralientauscli (1 829); Nees, Eur. Leberm. (1838).
Prond obcordate, spiar.sely furcate, margin thin, increasing by
joints from the apex, pores conspicuous, bearing the peduncle
from a sinus of the terminal lobe. Gemmæ wanting. Female
receptacle pedunculate, hemispherical, 4-G-lobed, rays of the
lobes shorter, rib-like, only iree at the inferior part, fibrous-barbu-
late underneath. Perianth obconicallj' campanulate, angular,
unequally 4 or 5 parted. Calyptra persistent, rupturing obliquely
at the apex. Capsule large, shortly pedicellate, dehiscing by
4 or 8 irregular revolute valves. Spores large, tuberculate.
Elaters short, bispiral. Male receptacle pedunculate, peltate,
repand, lobate.
Preissia commutata {Lindenb.), Nees.
Marchantia hemispharica, Linn. Fl. Suec. n. 1052 (1745).
Marchantía quaclrata. Scop. Fl. Cam. t. G3, 135C (1772).
Marchantia commutata, Lindenb. Hep. Eur. p. 101 (1829).
Marchantía androgyna, Tayl. iu Trans. Linn. Soc. xvii. p. 380 (1835).
Preissia commutata, Nees, Nat. Eur. Leber, iv. p. 117 (1838).
Preissia hemisphcerica, Cogn. in Bull. Soc. Bot. Belg. p. 49 (1872) ; Dum. Hep.
E u r. p. 152 (1874).
Chomiocarpon quadratus (Scop.), Lindb. Muse. Scand. (1879).
Dioicous, closely cæspitose, medium size, pale green to
brownish-green antioally, dark purple postically and at the
margin. Eronds prostrate, oblong-sinuate, apices bilobed,
porose, margin irregularly crenate, on the postical side
squamose, scales purplish-black, oblong, acinaciform. Female
flowers pedunculate, peltate, angularly hemispherical or suhquadrate,
sub-entire or lacerate, above obtusely 4-costate, 2-4-lobed,
loculi attached to the underside of the lobes, 1-3-frnited, dehiscing
irregularly. Perianth obconico-campanulate, 4-5-lobed.
Peduncle below red, above pale green, bicanaliculate, channels
on both sides with rootlet-threads. Calyptra rotundate,
styled, persistent. Capsule globose, shortly pedicellate, reddish-
brown or dark purple, dehiscing by revolute segments, cells
of the inner wall with reddish-brown ring fibres. Spores
brown, suhmuricate, roundish-tetrahedral. Elaters long, slender,
hispiral. Male receptacle pedunculate ; peduncle very thick,
obtusely angular and irregular in outline, outer walls dark
purple, 1 or 2 inner layers purple, others hyaline, trigones
large, walls thin, bicanaliculate, with rootlet threads in the
channels; smaller than the female, often snbsessile; peltate,
margin scariose, thin, undulate, irregular but undivided ;