80 
LAMINARIACE2E. 
IY. 
callus, erect, many times forked, fastigiate ; segments compressed above, patent? 
with acute axils.” J. Ag. Sp. Alg. vol. 1 , p. 1 71. Kiitz. Sp. Alg. p. 569- Ch. 
Pacifica and Ch. Atlantica , J. Ag. Liebm. p. 7- (Tab. IY. C.) 
Hab. On the Pacific coast of the Mexican Republic, Liebman. (v. s. in Herb. 
T. C. D.) 
Fronds many, from the same scutate base, 2-3 inches long, stipitate, soon forked, 
and then repeatedly divided dichotomously, the forks being closer and closer 
upwards ; equal in diameter throughout, subcylindrical below, compressed above, 
with acute apices. The axils of the forks are narrow and acute. Colour in a dried 
state very dark, brownish. I have not seen perfect fructification. 
I have not been able on the specimens which I have had an opportunity of 
examining, to make out the structure of the fructification with sufficient accuracy 
to authorize my introducing the cushions of spore-filaments into the plate. The 
above description is therefore chiefly translated from Prof. J. Agardh’s account of 
the genus. In aspect the plant resembles a very narrow Dictyota , but its substance 
is very much thicker, and a section under the microscope shows it to be composed 
of a much greater number of rows of cells. The surface cellules are very minute, 
and the cells increase in length and breadth as they lie more towards the centre of 
the flesh. 
Order III — LAMINABIACEiE. 
Laminarieae, Grev. Alg. Brit., p. 24. J. Ag. Synib. p. 4. Sp. Alg. p. 121 < 
Encll. 3rd, Suppl. p. 26. Kutz. Phyc. Gen. p. 344, and part of Chordece, p. 333- 
Sp. Alg. p. 573. Laminaridce, Lindl. Veg. Kingd. p. 22. 
Diagnosis. — Olive-coloured, inarticulate seaweeds, whose spores are superficial, 
either forming indefinite, cloudlike patches, or covering the whole surface of the 
frond. (Plants of large size , not much divided, usually stipitate, foliaceous.) 
Natural character. — Root rarely a simple, undivided disc ; commonly much 
branched, or only simple and disc-like when young. As the plant advances in 
growth, new accessory holdfasts are formed toward the base of the stipe round the 
primary one, and these, lengthening and branching, unite into a conical mass of 
rootlets (or cables), which together make up the compound root. Fronds of an 
olive-brown or an olive-green colour, mostly becoming darker on exposure to the 
air, in some cases turning green in drying ; usually tough and leathery in substance, 
