1s 
25. Aretium, Splifgerder. 
(Acrostichi § Aretium, Kunze.) 
Venation uniform, reticulated, areoles elongated, trapezoid or heaagonal. 
Sporangia few, irregularly disposed over the under side of the frond, 
often collected in small groups or lines.—Rhizoma creeping, elongated, 
jibrose, and furnished with lanceolate reticulated shining scales. 
Fronds in vernation lateral, articulated with the rhizoma, distant, 
uniform, oblong-elliptical, 6-10 inches long, smooth. 
1. A. citrifolium, Splitgerber, Enum. Fil. Surinam, p.7. Acrostichum 
citrifolium, Linn.; J. Sm. Gen. Fil. 
Has. West Indies, Introduced by Mr. W. Purdie. 
Oss. In my remarks on the genus Acrostichum, in the 4th 
volume of the ‘Journal of Botany’, I have noticed the pecu- 
harity of this fern. At that time I hesitated as to the propriety 
of separating it from the species with which I associated it ; 
since then I have had an opportunity of examining it in a living 
state and I have also become possessed of more perfect specimens, 
the examination of which has led me to follow Splitgerber in 
abopting Kunze’s sectional name “ Aretivm” for a separate 
genus. Having so done, I am further induced to consider 
Acrostichum crinitum as the type of another genus, leaving Acros- 
tichum aureum as the representative of the true Acrosticha. The 
most obvious distinction between the two latter is the habit, 
and this is also the case with Aretivm, which is further distin- 
guished by its few and scattered sporangia, a character not com- 
mon to any other of the Acrostichee that I am acquainted with. 
In aspect and venation Aretium approaches Antrophyum, but is 
readily distinguished by its creeping elongated rhizoma; that of 
- Antrophyum being cespitose. 
26. Dicryociossum, J. Sm. 
(Acrostichi sp., Sw.; J. Sm. Gen. Fil.) 
Venation uniform, reticulated, internal, areoles large, elongated, trapezoid 
hexagonal. Sporangia densely occupying the whole under side of the 
fertile frond, which is contracted.—Rhizoma caspitose, decumbent, 
densely furnished with criniform palea. Fronds in vernation ter- 
minal, adherent, oval-elliptical, one foot or more in length, criniferous, 
Jertile fronds shorter than the sterile, and somewhat contracted. 
— 1. D. enmitum, J. Sm. Acrostichum crinitum, Sw.; Hort. Kew.; Hook. 
et Grev. Ic. Fil. t..1. 
