184 
tridium marginatum Lesueur (der amerikanische Repräsentant von M. 
dianthus), Cereus sol Charleston (nahe mit (. bellis verwandt). 
Zur Charakteristik der neuen Gen. giebt Verf. folgende 
Diagnose: 
Stylatula Verr. Elongated, slender, nearly cylindrical; near 
the base naked, bulbous at the end. Pinnae short, supported by 
numerous strong radiating spines, the polypes clustered on their 
upper surface. Axis sub-cylindrical, extending through nearly the 
whole length. 
Parisis Verr. Corallum irregularly branching, nearly in a 
plane. The axis consists alternately of calcareous and suberous 
segments, :of uniform thickness, traversed by numerous narrow sul- 
cations. The branches originate from the calcareous segments. 
Coenenchyma persistent, rather thin, somewhat membranous, with 
a rough surface. Cells prominent, arranged irregularly on all sides 
of the branchlets, but ofter absent on the median surfaces of the 
larger branches. 
Titanideum Ag. Closely allied to Briareum, but has a 
more distinet axis, which is spongy and very spiculose, but firm 
and less porous than that of the latter. The cells are scattered on 
all sides and not prominent. 
Synaraeu Verr. (= Porites p. p.).. Corallum irregularly 
branched or glomerate. Cells without distinct walls, the septa ru- 
dimentary; six prominent paliform lobes surround the central ca- 
vity, which has a rudimentary or very small, tubercular columella; 
outside of the pali are other similar points or granulations, scat- 
tered between the cells, which are not distinetly eircumseribed, but 
ofter separated for some distance by a porous coenenchyma. 
Trachypora Verr. Corallum explanate, thin; below echi- 
nate and coarsely costate; above with scattered polyp centres de- 
stitute of walls, with ‚one or two cycles of septa, radiating at the 
centres, but becoming subparallel between them, as in Halomitra, 
strongely dentate or lacerately lobed, the strongest lobes surroun- 
ding the polyp centres ; columella loose, trabicular. 
Acanthopora Verr. Corallum ramose, solid, the cells being 
filled below as in Oculina. Costae between the cells represented 
by series of spines. It differs also from Echinopora in its polyp. 
Clavarina Verr. Corallum compact, branching. Üells im- 
perfectly eircumscribed, but not confounded in series. Septa and 
walls thickened, the former lacerate-toothed, with paliform teeth at 
the bases. Columella rudimentary. 
Aulactinia Ag. Column elongated, upper portion capable 
