IV. FUCACE^.— Fucus. 69 



tapering to the base and here and there toothed, secondary branches and receptacles 

 springing from the axil of the tooth. Air-vessels elliptical, from half an inch to two 

 inches in length, occurring at irregular intervals in the substance of the stem or 

 branches, and much wider than the parts around them. Receptacles lateral, pedicel- 

 late, ovate or globose, yellow when ripe. Spores four in each perispore. Colour 

 varying from a greenish to a fulvous olive. Substance tough and leathery. 



This species varies much in size, and in the comparative robustness of the 

 branches. When growing on the open sea shore, far removed from the influence 

 of fresh water, it attains the length of several feet, and a breadth of nearly half 

 an inch, the colour being of a dark bottle green. In deep bays or arms of the sea, 

 it is much less luxuriant, and more tawny. When growing in a?stuaries it 

 becomes of still smaller and feebler growth. I am indebted to Mr. Nicholas Pike 

 of New York for specimens gathered in Chelsea Eiver, Boston Bay, in which the 

 whole frond, though bipinnate and in fruit, is not more than six inches long, and 

 scarcely a line in diameter at the widest part. These specimens are without air- 

 vessels, but have all the other characters of the species. 



Another singular form, the Fucus scorpioicles of Flora Danica, t. 1479, has been 

 sent to me by Mr. Hooper from Fort Hamilton, New York Bay. This is nearly 

 as slender as that just mentioned, but is much more irregularly branched, having 

 a tendency to dichotomous division, with many irregularly placed, divaricating 

 lateral branches. I have compared it with a Norwegian specimen of F. scorpioicles, 

 with which it agrees very nearly. I was at first disposed to consider it identical 

 with the F. Machaii of British authors, but it is less regular in its branching than 

 that (supposed) species. Both are regarded by J. Agardb, and perhaps justly, as 

 varieties of F. nodosus. 



Sect. 2. Fucus, J. Ag. Frond flat, with a midrib. 



3. Fucus distichus, Linn. ; stipes filiform, expanding into a very narrow, linear, 

 dichotomous ribbed frond ; the margin very entire ; air-vessels none ; receptacles 

 terminal, subsimple, in pairs, elongate-linear, compressed. J. Ag. Sp>. Alg. vol. 1, 

 p. 209. Kiitz. Sp. Alg. p. 590. Turn. Hist. i. 4. Fl. Dan. t. 351. Lyngb. Hyd. 

 Dan. t. 1. 



Hab. Rocks between tide-raai'ks. Shores of Greenland and Newfoundland, 

 De la Pylaie. 



Frond 3 — 6 inches long, rising from a filiform stipe, which gradually expands 

 into an obsoletely ribbed, thickish lamina about a line in breadth and repeatedly 

 forked. Axils acute. Receptacles scarcely wider than the segments which they 

 terminate, linear, tapering to each end, from half an inch to an inch in length. J. 

 Ag. I. c. 



I am not acquainted with this species. 



