160 BRITISH SEA-WEEDS. 



very firmly to paper. The cord -like axis is very distinct 

 in some specimenSj and has the appearance of a midrib. 

 The spores are described by Professor Agardh as naked ; 

 but Dr. Harvey has since raised a doubt on this point 

 by discovering, with the aid of a high magnifying power, 

 what he believed to be the remains of a very delicate, 

 membranous pericarp. 



Order XVI. WRANGELIACEiE. 



Rose-red, thread-like Sea-weeds, with or without joints, tra- 

 versed hy a single-tuhed jointed axis. Fructification : — 

 1. Spores formed in the terminal cell of hranching threads, 

 which radiate in naked clusters, either from a fixed point or 

 round minute side-branchlets. * 2. Tetraspores formed of 

 hranchlets shortened to a single cell, naked, not present in 

 all the genera. 



Genus LXVII. WBANGELIA. 



Frond thread-like, much branched, jointed, one-tubed ; 

 internodes of the axis naked, or covered with minute cel- 

 lules; nodes clothed with opposite or whorled, jointed 

 hranchlets. Spore-clusters terminal in a nest of fibrous 

 hranchlets ; tetraspores naked, spherical, triangularly di- 

 vided, seated on the sides of the hranchlets. — "Wrangeha, 

 named in honour of Baron Von Wrangel, a Swedish na- 

 turalist. 



The species of this genus are not numerous, and are 

 mostly natives of warm or temperate latitudes. They 

 were formerly placed in the Order Ceramiace<s, between 

 the Griffithsia and Callithamnia, which they externally 

 resemble. They are removed to their present position 

 on account of important differences in their mode of. 

 fructification. 



