SUPPLEMENT. 



The following species, of which the author has not seen specimens, were inad- 

 vertently omitted from their proper places in the monograph. They are all con- 

 tained in the Nerei§ Boreali-Americana of Prof. Harvey. The following descrip- 

 tions and remarks are simply copied from the work mentioned. 



Tetraspora lacnnosa, Chauv. 



Frond at first tubular, then flat, or irregularly lobed, membranaeeo-gelatinous, pale-green, every- 

 where pierced with roundish holes of various sizes. Chauv. Alg. Norm. Breb. Alg. Fal.p. 

 11, t. 1. Kutz. Sp. Alg. p. 221. T. Godeyi, Be Breb. KiUz. Tab. Phyc.t. 30, /. 3. T. 

 perforata, Bailey, M.S. 



Hab. — In fresh-water streams. Abundant near Westpoint, Prof. Bailey ; Providence, Rhode 

 Island, Mr. Olney. (v. s. in Herb. T.C.D.) 



Frond at first funnel-shaped,- afterwards splitting open, and then flat, expanding upwards and 

 irregularly lobed, everywhere pierced with roundish holes of various sizes, large and small 

 intermixed. These holes increase in size and numbers with age, and thus at last the frond 

 becomes an open network. The substance is very gelatinous, but rather firmer than in some 

 other species of the genus. The color is a pale green; and the hyaline gelatinous membrane 

 is filled with roundish granules set in fours. 



Kiitzing's figure of T. Oodeyi answers well to our plant. I have not seen any 

 authentic specimens of T. lacunosa, which is referred by Kiitzing to his T. lubrica, 

 var. /?., but the description given of it applies to the American plant. When care- 

 fully dried, it forms a very pretty object for the herbarium. {Clilorospermece, p. 

 61.) (^Harvey, p. 61.) 



IVostoc (Hormosiphon) arcticnm, Berk. 



Fronds foliaeeous, variously plaited, green or brownish ; filaments at length (their gelatinous 

 envelope being dissolved) free. Berk, in Proc. Lin. Soc. fide An. Nat. Hist. 2d Ser. vol. 

 10, p. 302. 

 Sa6.— On the naked soil, in boggy ground. Assistance Bay, lat. T5° 40' N. Pr. Sutherland, (v.s.) 



"Fronds foliaeeous, variously plicate, sometimes contracted into a little ball. Gelatinous 

 envelope at length effused ; connecting cells at first solitary, then three together ; threads, 

 which are nearly twice as thick as in N. commune, breaking up at the connecting cells, so as 

 to form new threads, each terminated with a single large cell, the central cell becoming free." 

 Berk. I. c. 



"It grows," says Dr. Sutherland, "upon the soft and almost boggy slopes around 

 Assistance Bay; and when these slopes become frozen at the close of the season, 



29 October. 1872. ( 225 ) 



