130 
CHORDARIACEiE. — Ralfsia. 
iy. 
Y. RALFSIA. Berk 
Frond coriaceo-crustaceous, fixed by its inferior surface, orbicular, concentrically 
zoned, composed of densely packed, vertical, simple filaments, agglutinated 
together into a crust. Fructification , depressed warts, scattered over the upper 
surface, containing obovate spores , attached at the bases of vertical filaments or 
paranemata. 
The plants included in this group resemble the crustaceous lichens in outward 
characters, and, like them, spread over the face of rocks in varying patches. In the 
character of the fructification there is an approach to Dictyotacece , but the genus is 
retained in Chordariacece on account of the structure of the frond, and a supposed 
affinity with Leathesia. 
1. Ralfsia expansa , J. Ag. ; frond orbicularly expanded into a crust, lobed at 
the margin, flattish (?) in the middle, here and there raised in tubercles. J. Ay. 
Sp. Alg. 1, p. 63. 
On Madrepores in the Gulf of Mexico. Y era Cruz, Liebman. 
I have not seen this plant, and am uncertain whether I have correctly translated 
Prof. J. Agardh’s specific character, which is as follows : — “ Fronde orbiculariter 
expansa in crustam margine lobatam, medio subcontinuam hie illic in pustulas 
elevatam.” 
2. Ralfsia deusta , Ag., (not Berk.) ; frond concentrically lobed, the lobes sub- 
reniform, imbricated, longitudinally striate, concentrically zoned. J. Ay. Sp. Alg., 
1, p. 63. Fucus funyularis , FI. Dan. t. 420. 
Hab. On the shores of Greenland, Void. Unalaschka, Tilesius. 
Frond orbicular, 1 — 2 inches in diameter, adhering to the rocks, constituted of 
numerous lobes, one imbricating on the other. Colour chestnut brown. 
I am not acquainted with this plant. 
