50 
YALONIACE^. 
moderately high magnifying power it appears to he transversely striate. The primordial 
sac readily separates from the outer cell-wall. 
This plant was first noticed in the Mediterranean Sea, where it grows in the fissures 
of littoral rocks in many places. It occurs also in Brazil, from whence I possess a 
specimen ; and is found generally throughout the West Indian Islands. Our Key West 
specimens are rarely more than two inches high and about three in breadth. The 
largest specimen I possess was given me by the late Mr. Menzies, as having been 
dredged in twenty fathoms in the Gulf of Mexico. This specimen measures six inches 
across, and its venation offers some peculiarities ; which perhaps may lead to its specific 
separation. In our Key West plants the seriated cells of the principal veins stand apart 
from each other, or are in single file, leaving wedgeshaped spaces between. In Mr. 
Menzies’ specimen the principal veins are partly unicellular, partly formed of several 
parallel, closely placed cells, without interspaces. The structure is easily seen, but 
difficult to describe in intelligible language. Should subsequent observations establish 
this plant as a species, it may be called A. Menziesii. 
Plate XLIY. A. Fig. 1. Anadyomene fiabellata , full grown ; and Fig. 2, a young 
plant ; the natural size. Fig. 3 represents Fig. 2, magnified , to show the structure of 
the frond. 
Y. DICTYOSPHiERIA. Dne. 
Root consisting of a few grasping processes. Frond , a decumbent, amorphous mem- 
brane composed of a single series of vesicated, sub-globose, tough-coated cells, filled 
with green, fluid endochrome. Fructification unknown. 
The plant for which this genus was defined by Decais'ne was formerly referred to 
Valonia , to which no doubt it is closely allied, but from which it differs by the greater 
lateral coherence of the cells which compose the frond, and also by the structure of these 
cells. It is of common occurrence throughout the tropics of both hemispheres. On the 
coast of Australia a second species is equally common, differing from D. favulosa in the 
frond being never vesicated, and in the component cells being very much smaller, the 
surface flatter, and the frond having a silky lustre. This I have elsewhere described 
under the name I). sericea. 
1. Dictyospiijeria favulosa , Dne.', frond at first globose and hollow, afterwards 
irregularly torn, expanded ; the vesicated cells globoso-hexagonal, convex, and very 
prominent. Dne. An. Sc. Nat. Ser. 2. vol. 17, p. 328. Kiitz. Sp. Alg. p. 512. 
Valonia favulosa , Ag. Sp. Alg. 1. p. 432. (Tab. XLIY. B). 
