V. LAURENCIACEJ]:. 69 



site regions of the ocean of both hemispheres. Champia (as here understood) is 

 equally sporadic. Lomentaria ovalis is a native of the Pacific and Atlantic oceans. 

 Bonnemaisonia is European ; Cladhymenia and Delisia, Australian. 



The natural limits of the order are variously understood by botanists, and I have 

 the misfortune to differ from Prof. J. Agardh in my opinion on the subject. He 

 admits two suborders, Spongiocarpecc and Solieriece, which do not appear to me to 

 associate naturally with the other genera. Spongiocarpece, consisting of the 

 remarkable genus Polyides^ has a structure of frond and of fructification Avidely 

 different from that of either of the suborders here retained, and also, in my judg- 

 ment, from that of any other Desmiospermatous Order. The Solieriece, consisting 

 of Solieria and Eucheuma, appears to me to associate more naturally with Hypnea, 

 and to connect that genus in some degree with Gelidium. I formerly admitted 

 Chrysymenia and Chylocladia, J. Ag., and Thysanocladia, Endl. but the different 

 structure of the nucleus in these genera, as has been well pointed out by Agardh, 

 compels me to remove them elsewhere. Yet so similar in habit are some of the 

 species of Ckylodadia to some Lomentarice, that almost all authors have confounded 

 them. The presence of diaphragms in the frond is no certain test of a Lomentaria^ 

 as appears by Chylodadia aiticidata, whose sporiferous nucleus is identical with that 

 of CL clavellosa. 



SYNOPSIS OF THE NORTH AMERICAN GENERA. 



Suborder 1. BonnemaisonievE, J. Ag. Frond solid. Conceptacles ovate. Spores 

 pear-shaped, on simple spore-threads. 



I. Laurencia. 



Suborder 2. Lomentarie^. Frond, at least the branches, hollow, constricted 

 at intervals and divided internally, by transverse septa, into chambers. Conceptacles 

 ovate or spherical. Spores obconic or roundish, sessile, or attached to much 

 branched, confervoid, spore-threads. 



II. Champia. Conceptacles ovate, with a terminal pore. Spores paniculate, on 



branching spore-threads. 



III. Lomentaria. Conceptacles globose, without a pore. Spores sessile, or nearly 

 so. obconical. 



