MONORMIA. 285 



1. Trichormus incurvus Allm. 



Plate LXX7. Fig. L? 



Char, " Plant citlicr diffused through the toatcr or collected on 

 the surface. Filaments of a iiea-green colour, croioded 

 together confusedly in a gelatinous matrix, variously curved, 

 but never regularly spiral, assuming, when dried, a fine 

 verdigris-green colour loithout lustre.'''' — Allman. 



AUman in Annals of Nat. Hist. vol. xi. p. 163. 



Hah. In the Grand Canal dock, Dublin, October: Dr. 

 Allman. 



The only authentic specimen which I have seen of this 

 species was so much injured that I was not able to make an 

 examination of it in tlie least satisfactory. A specimen, how- 

 ever, sent me by INIr. Thomj)Son, collected by that gentleman 

 and found floating on the surface of Lough Neagh, at Shane's 

 Castle, marked Anahaina fios-aquce, accords so well Avith the 

 description and figure given by Dr. Allman of T. incurvus, 

 that scarcely a doubt remains as to the propriety of regarding 

 Mr. Thompson's plant as that species, see PI. lxxv. fig. 1. 

 From the true A. fios-aquce INIr. Thompson's si^ecimens differ 

 in the less considerable dimensions of the filaments, and in 

 the absence of the enlarged cells. 



Section ii. 

 Filaments invested in a mucous matrix of a definite form. 



37. :MONOilMIA Berhdey. 



Char. " Frond branched, composed of a single moniliform 

 thread, folloiving the ramifications, imyncrsed in gela- 

 tine:' —Bark. 

 Derivation. From jjlovos, one, and op^os, a necklace. 



This genus scarcely differs from Nostoc, between which and 

 Anabaina it forms a clear link. 



