66 FUCACE^.— Ctstoseiea. iv. 



Nearly related to the preceding genus, from -which it differs in the air-vessels, 

 which do not here run together into a compound vessel of many cells, though they 

 form little chains, one inflation of the branches succeeding another but remaining 

 separate. Upwards of twenty species are described, of which thirteen or fourteen 

 are found in the Mediterranean, and four occur on the Atlantic shores of Europe 

 as far north as Great Britain, reaching their highest latitude on the western coast 

 of Ireland. The group is scarcely represented in the New World. One or two of 

 the European species are stated, on doubtful authority, to occur on the shores 

 of Guiana and Brazil, where probably something else has been mistaken for 

 them ; but there is no record of any having been detected on the eastern shores of 

 America, where European forms might, more naturally, have been anticipated. 

 The only North American species with which I am acquainted is the following 

 from California. 



1. Ctstoseiea expansa, Ag. ; frond (its base unknown) very long, filiform, 

 slender, smooth, repeatedly pinnate, distichous, the ultimate ramuli simple or 

 forked ; air-vessels ellipsoidal, chained, several together in the lower half of the 

 penultimate and ultimate branchlets ; receptacles " cylindrical, warted, paniculate, 

 subconfluent with the tops of the branches." J. Ag. Sp. Alg., vol. 1, p. 226. Cystoseira 

 Douglasii, Han. in Bot. Beecheg, p. 407. Siropliysalis Douglasii, and S. expansa, 

 Kiitz. Sp. Alg., p. 603. (Tab. I. B.) 



Hab. Probably in deep water. At Monterey, California, Mr. Douglas ; Dr. 

 Coulter, (v. s. in Herb. T.C.D.j 



The root and lower part of the stem are unknown. Our specimens consist of 

 portions of stems (or branches) from two to three feet in length, and about 

 half a line in breadth, compressed, becoming narrower and more filiform toward 

 the extremities ; and thrice or four times divided in an alternately pinnate 

 manner. The ultimate ramuli show a disposition to become dichotomous. Air- 

 vessels from one to two lines long, ellipsoidal, in strings of four to eight, forming 

 swellings in the smaller branches and ramuli ; the string of swellings generally 

 commencing near the base of the ramulus, and extending at least through its lower 

 half In the ultimate and smaller divisions the inflations are proportionally fewer 

 and are sometimes solitary. I have not seen the receptacles which J. Agardh 

 describes as being " 6 — 8 lines long, everywhere of equal thickness, warted, and 

 nearly all pedicellate." 



This is probably a species of very great length, the portions of branches which 

 are aloiie known to us being evidently only the upper divisions. There is a 

 striking resemblance in habit between these and the most branching forms of 

 Halidrys osmundacea, but in the present species each vesicle stands perfectly apart 

 from its neighbour, however closely they may approximate. 



