28 Tr. E. FRITSCH. 
33. LYNGBYA ATTENUATA sp. 0. 
(Pl. II., figs. 79-84.) 
Filis stratum definitum non formantibus, sed numerosis ad superficiem stratuum 
Phormidii athxis vel repentibus, flexuosis, fragilibus ; vaginis achrois firmis tenuibus ; 
trichomatibus inter cellulas haud constrictis, cellulis tam longis quam latis vel paulo 
brevioribus, cytoplasmate homogeneo dilute zrugineo, dissepimentis pellucidis, valde 
indistinctis ; apice trichomatis plus minusve distincte attenuato, plerumque rotun- 
dato, interdum paulo capitato, saepe modice arcuato. 
Diam. fil, = 5=6 25 diam. trich;= 4°8—5-7 p. 
Hab.—Pond in ice off Black Island, McMurdo Strait, December 31st, 1902; 
Gap pond, Winter Harbour; pond among the eskers which border the shore of the 
Western mainland, December 2nd, 1902. | 
The most distinctive character of this species lies in the marked attenuation 
of the apex (figs. 79, 80), the terminal cell being sometimes somewhat inflated 
and making the trichome capitate (figs. 82, 83); as a general rule the attenuated 
apex is rounded, but occasionally the terminal cell is more or less pointed (figs. 
81, 84). Iodine coloured the filaments a deep yellowish-brown, but left the apical 
cell colourless. 
I. attenuata appears to come nearest to L. xruyineo-ewrulea (Kiitz.) Gom., 
from which it differs in the following respects: the frequent curvature of the apex 
of the trichome; the rather longer cells; the homogeneous cell-contents and the 
absence of granules at the dissepiments; the generally marked attenuation of the 
end of the trichome, often beginning at some distance from the apex; the absence 
of special thickening of the outer membrane of the apical cell; the very indistinct 
septa.  L. cladophorze Tilden (Minnesota Algae, I, Minneapolis (1910), p. 116, 
Pl. V., fig. 84) should also be compared. 
34. LYNGBYA ®RUGINEO-C@RULEA. 
(Pl. II., figs. 85-86.) 
Lyngbya erugineo-carulea (Kiitz.) Gom., tom. cit., pp. 146-147, Pl. IV., figs. 1-3. 
Hab.—Abundant in Gap pond, Winter Harbour, on the surface of the 
Phormidium-sheets, where it often formed an appreciable stratum. 
In some cases the cell-contents were provided with abundant coarse granules 
(fig. 85), in others some of the dissepiments were very markedly granulated (fig. 
85a). In several of the samples from the Gap pond the filaments of this species 
were forming gonidia, a single round gonidium being observed in each cell (fig. 86). 
