88 BEITISH SEA-WEEDS. 



of both kinds on the margin of the frond or in the axils of 

 the teeth. 



This plant, when growing, is of a deep blood-red 

 colour ; but becomes dark purple, almost black in dry- 

 ing. In this country it is confined entirely to the shores 

 of Scotland and of the northern counties of England 

 and Ireland, and within these limits occurs pretty fre- 

 quently, being most abundant in the higher latitudes. 

 I have gathered it on the coast of Yorkshire, near 

 Whitby, and so far as I am aware, this is the most 

 southern habitat that has been recorded. 



Genus XXXVII. CHONDEIA. 



Fronds ■ thread-like, cartilaginous, pinnately divided, 

 coated with small, many-angled, irregularly placed cells ; 

 axis jointed, many-siphoned ; branchlets club-shaped, ta- 

 pering abruptly at the base, obtuse, or nearly so, at the 

 tip, transversely striped. Fructification : — 1. Tufts of 

 pear-shaped spores on simple threads radiating from a basal 

 placenta contained, within a cellular pericarp, in ovate, per- 

 forate conceptacles, borne, either on stalks or sessile, on the 

 branchlets. 2. Tripartite tetraspores crowded irregularly in 

 the club-shaped branchlets. — Chondria, from tlie Greek 

 chondrus, cartilage. 



This is a large genus, but has only two representatives 

 among our native Sea-weeds. The species that compose 

 it were formerly arranged among the Laurenciae, which 

 they resemble in external appearance, but from which 

 they differ in structure. Th& many-siphoned, jointed 

 axis of the stem is the character that is principally re- 

 lied on to separate the two genera. 



