38 DASYCLADEiE. 



11. DASYCLADUS. Ag. 



Frond destitute of calcareous crust, soft, and flaccid, cylindrical or club-shaped, 

 unbranched, composed of a tubular, unicellular filiform axis, beset throughout with 

 closely placed whorls of trichotomous, horizontal, articulate ramelli. Sporangia 

 globose, affixed to the nodes of the ramelli, and containing, at maturity, very numerous 

 spherical spores. 



Small, densely tufted, erect plants, with almost spongy fronds, so densely are the 

 ramelli frequently inserted. Their substance is very soft and flaccid, but tough, and 

 the colour a full dark green. The membrane composing the frond is every where 

 hyaline, and becomes glassy when dry ; the colouring matter is viscid and granular as 

 in Bryopsis. The genus was founded by Agardh on D. davceformis, a common Alga 

 in the Mediterranean ; and Meneghini has described a second species from the 

 Adriatic. I now venture to add a third, which I was formerly disposed to consider 

 as identical with D. davceformis. 



1. Dasycladus occidentalis ; whorls sub-distant ; apices of the ramelli very 

 obtuse. (Tab. XLI. B.) 



Hab. On rocks between tide marks, on the Florida Keys, Key West, Dr. Wurde- 

 mann, W. H. H. Key Biscayne, Prof. Tuomey. (v. v.) 



Root discoid, throwing out a few clasping fibres. Fronds mostly densely tufted, 

 sometimes solitary, 1-2 inches high, clavate, from a line to nearly half-an-inch in dia- 

 meter (including ramelli) erect, straight or curved, destitute of calcareous incrustation ; 

 consisting of a filiform, unbranched, unicellular axis, whorled throughout with densely 

 inserted polychotomous ramelli. The axial filament varies in diameter from the thick- 

 ness of a human hair to twice the diameter of hog's bristle ; it is cylindrical, with a 

 continuous cavity filled with endochrome, and seems to be developed from a single cell. 

 Its wall is very thick, tough, and composed of several distinct layers of cellulose, con- 

 centrically deposited. The filament is marked externally, at short intervals, varying 

 in distance in different specimens, with transverse rings or nodes, which give an appear- 

 ance of joints (but there are no internal septa) ; and immediately above each node from 

 six to twelve horizontal ramelli are inserted in a whorl, and in denuded specimens 

 their places are indicated by a whorl of disc-like scars surmounting the node. The 

 ramelli vary much in length and in density. In some specimens the internodes are 

 so short that the frond seems continuously clothed, like the spongy frond of a Codium, 

 from base to apex ; the axis being completely concealed by the ramelli. In others the 

 internodes are as much as a line in length, and the whorls appear sub-distant, like 

 those of a Myriophyllum. Sometimes the ramelli are scarcely a line long ; in other 

 specimens they are 2-3 lines or more. In all cases they are tri-dichotomous, twice or 



