68 LAURENCTACE^. v, 



of abbreviated branches or ramuli, or they are sessile on the sides of the branches. 

 Their sporiferous nucleus exhibits considerable modification in the different genera. 

 In the Bonnemaisoniece the spores are properly pear-shaped, rounded at the apex, 

 and taj)ering at the base into a very slender spore-thread or funiculus of which the 

 spore is the enlarged and fertile terminal cell. These spore-threads are always 

 unbranched ; in some species very short, in others long, and either rising in a tuft, 

 from the base of the cavity, or from a cellular basal placenta, which occasionally 

 fills up a considerable part of the cavity and is divided into several lobes. In the 

 Lom.mtariece the spores are more properly obconical than pear-shaped, truncate at 

 the apex and tapei'ing but slightly at the base. In Lomentaria {Chylocladia of 

 British writers, not of Agardh) where they taper most to the base, they are nearly 

 sessile, radiating from a central point and closely packed together into a spherical 

 nucleus. In Champia they are sometimes shortly obconical, and sometimes ellip- 

 soidal or oblong, and are borne on a much-branched, confervoid placenta, each spore 

 being formed in the terminal cell of one of the branches. Yet these two genera 

 are so similar in aspect and in the structure of the frond that many species of the 

 latter have by most authors been referred to the former. 



The tetraspores (known only in Laurencia, Lomentaria and Champia) are tripartite, 

 that is, formed of four pieces of unequal size so placed together that three only are 

 visible on a front view, and are dispersed without order either through all the 

 branches, or through the suialler ramuli, where, in some cases, they are collected 

 in a sub-defined cluster near the apices. In this character is found the chief 

 technical distinction between the Bonnemaisoniece and the RJwdomelacece. The 

 Lomentariece are additionally known by the peculiar structure of the frond and the 

 differences, indicated above, in the sporiferous nucleus. 



The colour of the frond in this order is considerably varied in the different ge- 

 nera, and even in the same species under different circumstances. Bonnemaisonia^ 

 Delisia, and Asparagopsis (Lictoria) are of a most beautiful rosy pink ; Lomentaria 

 and Champia, when in good oi'der, are a purple lake, sometimes reflecting rainbow 

 hues ; but their colours are fugacious and, when the fronds grow in sunny places, 

 they very frequently are either greenish, yellowish or nearly colourless. The 

 proper colour in most Laurencice is a lurid purple, in some brown-red ; but light 

 and exposure in shallow water call forth every shade of red, orange and yellow, 

 and sometimes green, the same frond often being variegated with two or more of 

 these tints. Almost all decompose rapidly in fresh water, especially if again moist- 

 ened after having once been dried. 



The substance of the frond is either cartilaginous or gelatinoso-raembranaceous. 

 The taste insipid or somewhat pungent. Laurencia jnnnatijida, the Pepper Dulse of 

 the Scotch, was or is eaten as a salad in parts of Scotland {Lightf. Fl. Scot. p. 954). 

 According to Dr. Lindley, a large portion of what is now sold in the shops as 

 Corsican Moss is Laurencia ohtusa, which perhaps has equal virtues with the real 

 Helminthochorton. 



This order, though small, is widely dispersed, being represented under one form 

 or other in almost every sea. Laurencia is peculiarly cosmopolitan in its distribu. 

 tion, and its common forms, L. pinnatijida, ohtusa, &c. are found in the most oppo- 



