HASSALLIA. 231 



23. HASSALLIA Berk. 



Char. (t Branches increasing by the elongation and division 

 of a single cell." Berk. 



The above definition, like that of Scytonema, embraces only 

 the essential character of the genus, to it, other well marked 

 peculiarities maybe added; such'as the rigidity of the filaments, 

 the branches usually solitary, and the beaded form of the cells. 

 The genus therefore may otherwise be defined thus : 



Char. Filaments somewhat rigid, of unequal diameter. 

 Branches usually solitary, formed by the elongation and 

 division of a single cell. Cells distinctly moniliform, usu- 

 ally in a single series. 



Kiitzing's genus Sirosyphon is thus specified : it includes 

 but a single species, and cannot be said to fulfil the intention 

 of the genus Hassallia. 



" Trichomata parenchymatica ex cellulis gelineis in vagina 

 lamellosa, apice clausa longitudinaliter striatis, apice in arti- 

 culos epenchymaticos confluentes transeuntibus compositum. 

 Spermatia insterstitialia. Rami basi geniculati." 



The above characters seem to me to be only of specific and 

 not generic importance. 



The genus Hassallia was instituted by the Rev. Mr. 

 Berkeley a considerable time ago : that gentleman, however, 

 delayed publishing it, and conceived on the appearance of the 

 " Phycologia Generalis " that it was frustrated by Kiitzing's 

 genus Sirosyphon, which I cannot think that it is. 



1. HASSALLIA OCELLATA Hass. 

 Plate LXVIL Figs. 2. 7. 6. 



Char. Branches solitary, divaricating, slightly contracted at 

 the base. Cells beaded. 



Conf. ocettata Dillw. t. D. Conf. ocellata E. B. t. 2530. ; 

 Harvey, in Hook. Brit. Fl. p. 364. Scytonema occllatum 

 Harv. in Manual, p. 154. 



