326 Mr. J. Ralfs on the Nostochinese. 



Monormia*, Berkeley. 

 Frond definite, gelatinous, elongated, linear, spirally curled and 

 convoluted, inclosing a single continuous moniliform filament. 



Monormia is very closely allied to Trichormus, Allman, differ- 

 ing principally, if not solely, in its definite linear frond, which 

 incloses a single moniliform filament to be traced throughout all 

 the peculiar convolutions of the frond. The vesicular cells are 

 interstitial and occur singly. The sporangia are numerous, and 

 are first formed from the cells at the greatest distance from the 

 vesicular cells. 



Without due attention Monormia might easily be mistaken 

 for a species of Nostoc, but the mass formed by its convoluted 

 frond is not inclosed by a common membranous pellicle as in 

 that genus. 

 Monormia intricata, Berk. Gleanings of British Algae, p. 46. t. 18 



(1832); Harvev, Man. of Brit. Algae, p. 185; Phycologia Bri- 



tannica, t. 256 f Hassall, Brit. Fresh. Algse, p. 286. t. 75. fig. 11. 



Nostoc intricatum, Meneghini, Mon. Nostoch. Ital. p. 122 (1842). 



Anabcena intricata, Kiitzing, Phycologia Germanica, p. 1 71 (1845); 



Species Algarum, p. 288 ; Tabulae Phycologicae, p. 50. t. 94. fig. 1 . 



In ditches of the marsh to the south of Frindsbury Canal, near 

 Gravesend, Rev. M. J. Berkeley; in brackish ditches at Shirehampton, 

 near Bristol, G. H. K. T. ; near Wareham, Rev. W. Smith. Germany, 

 Kiitzing. 



This species occurs in slightly brackish ditches as floating ge- 

 latinous masses, each about as large as a walnut, and usually of 

 a reddish brown colour. When a small portion of the plant is 

 examined with a lens of moderate power, it is seen to consist of 

 an elongated continuous moniliform filament included in a de- 

 finite linear gelatinous sheath, which is very much curled and 

 convoluted, and the apposed surfaces of which are more or less 

 coherent. The vesicular cells are somewhat oblong, and rather 

 larger than the nearly spherical ordinary cells. The sporangia 

 are numerous, twice the diameter of the ordinary cells, and per- 

 fectly spherical. 



When the sporangia are mature the definite outline of the 

 linear frond is almost lost, and then there is little to distinguish 

 the plant from Trichormus but the peculiar convolutions of the 

 moniliform filament. The original colour of the gelatinous frond 

 has also then disappeared, and the plant has assumed a pale 

 greenish tint. 



In drying, the plant stains paper of a deep blue or purplish 

 colour. 



Plate VIII. fig. 1. 



* Bv Mr. G. H. K. Thwaites. 



