U2 WRANGELIACE^. v. 



sporiferous nucleus in these genera is widely diiFerent. In Callithamnion the nucleus 

 is a naked favella or encysted cell filled with a mass of disconnected spores origina- 

 tino- in the repeated division of the endochrome of the mother cell ; in Wrangelia, 

 as already described, it is a tuft of spore-threads bearing pear-shaped pedicellated 

 spores. If therefore the structure of the nuclei is to be our guide in arrangement, 

 the resemblance of Wrangelia to Callithamnion is one of analogy only, these genera 

 representing each other in the series to which they respectively belong. 



Naccaria, which is associated with Wrangelia by Prof. J. Agardh, appears at first 

 sight to have little afiinity with it, difi"ering especially in the wholly inarticulate 

 frond. This character is, however, of minor importance, as is seen in Cera^niacea', 

 where some genera are inarticulate ; or even in Wrangelia itself, where the older 

 portions of the stem and branches in several species are opaque. A comparison of 

 the sporiferous threads of Naccaria Avith those of Wrangelia will show an agree- 

 ment in essential structure ; and the diffex^ences in the nuclei are chiefly in the 

 arrangement of the parts, the spore-threads of Wrangelia radiating from the end of 

 a truncated branch, those of Naccaria being whorled round the ramuli. I think, 

 therefore, a true relationship between these genera has been established. 



WRANGELIA. Ag. 



Frond filiform, decompound-pinnate, articulated, one-tubed ; the intemodes naked 

 or coated with minute cellules, the nodes clothed with opposite or whorled, byssoid, 

 articulated ramelli. Sporiferous-nuclexis terminal, involucrated, the involucre 

 formed of byssoid ramelli, the nucleus composed of a dense tuft of radiating pyri- 

 form spores, formed of the terminal cells of the spore-threads. Tetraspores naked, 

 sessile on the sides of the ramuli, spherical, triangularly divided. 



In some species the frond is pellucidly articulate throughout, each internode 

 formed of a single, cylindrical, thick-walled cell, filled with a brilliant carmine 

 endochrome, and separated from the internodes above and below it by a hyaline 

 diaphragm. In others the younger parts of the frond alone exhibit this perfectly 

 articulated structure ; the older portions being more or less fully coated with a 

 stratum of small cellules ; and in some other species the whole of the stem and 

 branches are rendered opaque by these accessory cells, and the articulated structure 

 of their fronds can only be ascertained by a careful dissection. In all the species 

 the ultimate ramelli, which are often of a byssoid tenuity, are single-tubed and 

 pellucidly articulate, and they generally spring from each node throughout the 

 frond. They are minute, pinnately or dichotomously compounded, mostly whorled, 

 but sometimes distichous, and, in that case opposite each other. It frequently 



