NAIAS. 181 
scarcely demonstrable, but as the funicle of the embryo is 
notof an ordinary structure in this, and a lining may be as- 
certained in the innermost coat of the others, I prefer main- 
taining the opinion which I have long held, that it is tke 
podosperm in Ceratophyllum, Ruppia, etc. which is so enor. 
mously developed. 
Instances of adhering very fine embryonary sacs are not 
uncommon. 
I. Potamogeton. Fl, spicati hermaph. Perianth 4-sepalia. 
Stam. 4. Sepalis opposit. ovaria 4, sepalis alternantia. Ovulis 
campanulitropis. Fructus.— 
Flores herbacei. 
II. Aponogeton. Fl. spicati hermaph. Sepalis 2 ега 
bus, 3 tio postico о. Stam. 6-3 longiora, sepalis alternantia. 
Ovaria 3, rostrata, staminibus brevioribus oppositis. Capsule 
farinacez, seminibus pluribus, testa sulcata, membranacea. 
Embryo orthotropis, cotyledone magna, (radicula, brevi, 
plumula in rima recondit.) 
Rappia. Spadicos. hermaph. Per. o. Stam. 4 (unilocul.) 
Ovaria 4. Stigmata discoidea angulato-reniformia, ovula pen- 
dula anatropa. Fruct. drupacea. Embryo radicula maxime in 
cotyl. subito constrictis; cotyledonia teretiuscula, brevi, pressed 
down on upper end of radicle. 
III. Zanichellia, fl. monoici, masc. Stam. 1, nudum. Fem. 
Perianth cupuliforme. Ovar. 2-4 uni-ovulata, stigmatibus (just 
exserted,) reniformi-cordatis, ovulum pendulum antitropum. 
Embryo radicula maxime, cotyledone subulato-longissim. ver- 
natione circinnato, (transversely.) Plumula recondita. 
IV. Naias. Monoici Fl. solitarii. Masc. anthera bi-perian- 
thio membranaceo celluloso apice aperto. 
Fem. axillares, nudi, ovarium ovulo unicoerecto. Stylo bi- 
partito. Stigmata bina linearia. 
NAIAS. 
]. Naias rigida. Griff. 
[Foliis carnosis rigidis (e tela composita cellulosa,) alternis, 
