MARINE ALG/E. 7 



It might be urged that L. t/i-itit<!if<>l!<i and L. .Omnium* are sufficiently distinct 

 from Lessonia to constitute a separate genus ou account of the following characters : 

 The laminae are huge and undergo no multiplication by longitudinal splitting, the stem 

 is poorly developed and exhibits no rings of secondary thickening, and no lacunas are 

 present in laminae and stem; moreover, L. i/i'mnlij^Hn is markedly characterised by 

 the presence of numerous trumpet-hyphse in the medulla, as also is L. simulans to a 

 lesser extent. But though, at one time, we were tempted to separate these species from 

 Lessonin, we feel that such intermediate links as L. laminarioides and L. ovala are too 

 strong to admit of a generic separation, however great the contrast may be between our 

 plants and the typical dendroid species, L. fuscescens and L. nigrescens, upon which 

 the genus was founded. Further, we would suggest that whereas L. fuscescens and 

 L. iilt/n'scens are evidently sturdy perennials, L. grandifolia and L. simulans, with their 

 weak stems, may possibly be mere annual or biennial plants. Moreover, as mentioned 

 in the introduction, the local conditions of life in the Antarctic Ocean are peculiar, and 

 though during the long winter night the growth of our two species may be inhibited, or 

 even replaced by decay, yet during the perpetual daylight of summer they may 

 possibly have a special capacity for rapid growth, and thus perhaps attain in one season 

 the huge dimensions of our specimens. If such be the case, we would suggest that the 

 trumpet-hyphse, the actual function of which is unknown to us, may perhaps facilitate 

 rapid growth by providing channels for the ready transference of food-material and 

 waste products. That these trumpet-hyphse are connected in some way with the local 

 conditions of life seems evident from the abundant occurrence of similar ensheathed 

 hyphjo in fic.vnfirexfiit /KirwyniHi (figs. 14a, 13b), an Antarctic species which grows to a 

 considerable length. 



4. DESMARESTIA HARVEYANA. 



(Plate III., figs. 11-15.) 



Dismnrcxtia Imrrri/niKi, Gupp, Journal of Botany, 1905, p. 10G (tigs. 11-15). 

 D. media, Hook. f. et Harv. Flor. Antarct. II. (1817), p. 4DG ; Kutzmg, Tab. Phyc. IX. (1850), tab. 05, 



fig. II. ; hand (-irev. Synops. (1830), p. XL. 



D. (ifiili'iiln. var. i-iiiiijir/'std Reiusck in Flora, 71 (isss), p. 100 ; et in Intmiat. Polarforsch. 1882-1 ss: 1 ., 

 iMitsch. Exped. I'.an.l II. (1X00), p. .Ki8, tab. XVII., fig. 3. 



Off Cape Wadsworth, Coalman Island, 18 fathoms ; Cape Adare, February 24, 1904. 



Geogr. Distrib. Cockburn Island. South Georgia. 



Specimens of this plant were preserved both dry and in formalin. One of the 

 latter is as much as G feet long, but being incomplete, must have been longer still when 

 growing. They agree absolutely with those from Cockburn Island, collected by D. Lyall 

 on Ross's Antarctic Expedition (1839-1842). Lyall's specimens in the British Museum 

 are named D. iin't.lin in Harvey's MS. Harvey, indeed, was strongly of opinion that 

 they are identical with D. media Grev., i.e., Sj.mrvcltnus mtdhia C.Ag., collected at 

 Unalaschka by Chamisso, and figured by C. Agardh in his lcn. Alj. /'///., tab. 1C 

 (1822). Although we have not seen Agardh's type, we are so convinced that it is 



