24 RICCIACEAE 
Arnell, to which Herr M. Heeg refers in the Botaniska Notiser 
for 1898 (p. 21) and which we have been privileged to examine 
through the courtesy of Dr. Arnell. The antheridial ostioles in 
the European plant so far as we have been able to discover them 
in specimens kindly communicated by Herr Stephani, Herr Heeg, 
and others, seem to be very slightly or not at all elevated, yet in 
the Siberian specimens to which allusion has already been made 
they sometimes attain the height of .12 mm. above the surrounding 
surface, which is in excess of anything we have observed in the 
Californian specimens. 
In only one case have we noticed the partial exsertion of the 
sporangium at maturity as figured and emphasized by Bischoff in 
his original diagnosis of R. sorocarpa. In regard to this character 
Herr Heeg remarks: “ die von Bischoff besonders hervorgehobene 
Berstung der Lauboberflache bei der Fruchtreife, bezeichnet das 
Endstadium einer Entwicklungsperiode und wird nur selten gerade 
in diesem Zustande aufgesammelt." * 
6. Riccia Americana sp. nov. 
Riccia lamellosa Americana М. A. Howe, p. p. Bull. Torr. 
Bot. Club, 25: 189. 1898. 
Thallus rather loosely subradiate or forming compact more or 
less imbricate masses; principal divisions 5-15 mm. long, 1—3 
tmes dichotomous, very rarely simple, 2.5-4 mm. in greatest 
(polyoicous ?): antheridia infrequent, their ostioles not at all or 
slightly elevated: spores brown, 90-126 и in maximum diameter, 
obscurely angular, wholly destitute of a wing-margin, with 8—12 
clearly defined areolae, each about I5 іп width, across the outer 
нса сия 
* Неер, Bot. Notis. 1898: 20. 1898. 
