CRYPTONEMIACE^E. 138 



fruit in this order as there is in the substance of the frond. 

 In the simplest and most characteristic forms the favellidia 

 or masses of spores are immersed in the substance of the 

 frond itself, either wholly concealed beneath the surface cells, 

 or their place is indicated by a minute pore through which 

 the spores are finally liberated. Such a fructification differs 

 from the coccidium (the proper fruit of the two preceding 

 orders) in the absence of any definite pericarp. But it is 

 difficult to deny pericarps, in the same sense of that word, 

 to Gigartina and Gelidtvm, or even to Catenella. Insensi- 

 ble gradations connect the properly immersed favellidia of 

 Halymenia with the conceptacular fructification of Gigartina; 

 and, in doubtful cases, plants of this order are to be known 

 from Rhodymeniaceae more by the fibroso-cellular structure 

 of the frond than by difference in conceptacular fructifica- 

 tion. The tetraspores are in the less organized genera 

 attached to the threads of the periphery, and scattered over 

 them ; in many others they are immersed among the peri- 

 pheric threads, and appear to be formed from one of the 

 cells of the thread. In others, several consecutive cells are 

 so transmuted ; and sometimes the periphery bulges out into 

 warts of irregular size and shape, called nemathecia. When 

 these warts first appear they consist wholly of vertical fila- 

 ments in no respect different from those of other portions of 

 the peripheric stratum, but after a time each thread is changed 

 into a string of bead-like tetraspores, a structure beautifully 

 shown in Gymnogongrus Griffithsiae. The common form of 

 the tetraspore is tripartite, but many species have cruciate 

 tetraspores, and others have zoned ones. 



This is the largest, as well as most multiform, order of 

 Rhodosperms, and is, under one form or other, widely dis- 

 persed. Several of our genera are cosmopolitan, and even 

 some of the species are dispersed through most parts of the 

 temperate and tropical ocean. Gelidium corneum is found 

 on all the shores of Europe, and at both sides of the Ameri- 

 can Continent, as well as in South Africa and New Holland ; 

 and GrateloupiaJiHcina, which perhaps attains its northern 

 limit in the South of England, is very widely scattered along 

 the shores of the warmer parts of the Atlantic, and abounds 

 in the Mediterranean and Indian Oceans. Gigartina acicu- 

 laris and G. pistillata are both natives of the Southern Ocean ; 

 G. mamillosa has been brought from California. Gymno- 

 gongrus plicatus is equally widely dispersed. Gigartina 

 Teedii, so rare with us, is a common plant in the south of 



