Mr. J. Ralfs en the Nostochinese. 329 



3. T. Thwaitesii (Harv.). Filaments moniliform, slightly flexuose ; 

 ordinary cells globular or nearly so ; vesicular cells larger, globular 

 when interstitial, ovate when terminal, ciliated ; sporangia oval, 

 catenate. Sphcerozyga Thwaitesii, Harvey, Phycologia Britannica, 

 t. 113 B (1847). 



Salt-marshes, Dolgelley, North Wales, and Hayle, near Penzance, 

 J. R. ; Shirehampton, near Bristol, Mr. Thwaites ; Portbury, Somer- 

 setshire, Mr. Broome ; near Hastings, Mr. Jenner. 



Trichormus Thwaitesii forms thin, gelatinous, dark green 

 patches either on the damp soil covered at spring-tides or at the 

 bottom of brackish ditches or pools. Filaments moniliform, 

 elongated, pale bluish green. Ordinary joints nearly orbicular, 

 except when dividing. Vesicular cells interstitial and terminal, 

 ciliated, twice as large as the ordinary ones, ovate when terminal, 

 otherwise spherical. Sporangia oval or nearly globular, larger 

 than the ordinary cells, beginning near the centre of the fila- 

 ment and forming chain-like groups of six or more together. 



Mr. Thwaites' s specimens vary in some respects from those I 

 have gathered. I find the stratum very thin and tender, and the 

 sporangia rarely produced ; but Mr. Thwaites informs me, that at 

 Bristol, on the contrary, it forms, after a time, large, floating, 

 gelatinous masses, and then abounds with sporangia. 



Trichormus Thwaitesii is more likely to be confounded with 

 immature specimens of Sphcerozyga Carmichaelii than with either 

 of the preceding species of this genus, especially as they often 

 grow intermixed. In the present plant however the filament is 

 longer, the ordinary cells are more globular, and the terminal 

 cell either resembles the others or is ovate and vesicular. Its 

 ciliated and globular vesicular cells distinguish it from T, oscil- 

 larioides and T. recta. 



A specimen oiAnabaina variabilis sent me by Professor Kiitzing 

 is apparently identical with the present species ; but, as the former 

 is described as lacustrine, with attenuated ends, I have thought 

 it advisable not to unite them*. 



Plate VIII. fig. 4. a, immature filament ; b, mature filament. 



4. T. oscillarioides (Bory). Filaments elongated, flexuose; ordi- 

 nary joints subquadrate, distinct ; vesicular cells barrel-shaped or 

 elliptic, naked ; sporangia oval, catenate. Anabcena oscillarioides, 

 Bory, Diet. Class. d'Hist. Nat. Sphcerozyga oscillarioides, Kutz. 

 Species Algarum, p. 291 (1849); Tabulae Phycologicse, t. 96. fig. 5. 

 Trichormus affinis, Ralfs in lit. 



Brackish ditches. Shirehampton, near Bristol, Mr. Thwaites. 



* " Anabaina variabilis, lacustris, mollis, viridi-rcruginea ; trichomatibus 

 attenuatis, aerugineo-viridibus, laxe implicatis ; articulis ellipticis, majoribus, 

 granulosis." — Kiitzing, Phyc. Gener. p. 210. 



