180 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



Frond monosiphonous, coated more or less with cells. Con- 

 ceptacles external, consisting of a nucleus inclosed in a moutli- 

 less perithecium. Nucleoli several, formed of branched threads, 

 whose upper cells produce spores by division of their endo- 

 chrome ; spores at length conglobated. 



154. The few remaining Rhodosperms with filiform and mo- 

 nosiphonous threads, contained in this division, are distinguished 

 at once by their fructification. In the present case the com- 

 pound nuclei are lodged in an external conceptacle. They are 

 formed from fascicles of threads springing from a common point, 

 whose upper cells produce a multitude of spores by the re- 

 peated division of their endochrome. The frond is composed 

 of a central thread coated with more slender filaments, or in 

 some parts with cells, and is repeatedly branched, cylindrical, 

 or slightly compressed, and clothed with decidvious articulated 

 branchlets. The division consists of a single genus, whose 

 species afitect, for the most part, tropical or sub-tropical seas, 

 extending as far south as Tasmania. Two Or three are found 

 in the Indian Ocean, and one of these occurs on the coast of 

 Brazil. One species only occurs in the south of England, and 

 extends as far as Algiers, and on the eastern coast of North 

 America it has an analogous range. Dr. Harvey conjectures 

 that Ballia, a beautiful sub-tropical genus exactly analogous 

 to Sphacelaria, may be closely allied. At present, however, 

 its fruit is imperfectly known. 



3. Cryptonemiace^, Harv. (Cryptonemece, &c., J. Ag.) 

 Frond inarticulate, varying in texture, composed of arti- 

 culated threads closely incorporated, or, in the membranous 

 species, of cells. Nucleus sunk or contained in an external 

 conceptacle, simple or compound. Spores conglobated. 



155. The distinctive difference between this and the following 

 division, consists in the spores being disposed without order 

 in the nuclei. It comprises species differing greatly in struc- 

 ture as regards the frond, for while some are composed entirely 

 of filaments compacted together, others are as decidedly cellu- 

 lar. The genera are numerous, and are sei^arated by Agardh 

 into two sections, Gigartinece and Gryptonemew, one of them 

 characterised by a compound (Fig. 44, c), the other by a simple 



