544 University of California PuhUcations in Botany [Vol. 8 



the " Mesogloiaceae " (also in the narrower sense of the genus Meso- 

 gJoia, as limited by the type species of the genus M. vermiculata) both 

 because of the method of terminal growth ("trichothallic" as con- 

 trasted with "subapical") and because neither in Chordaria. nor 

 Mesogloia (as limited to conform with the type species in each case) 

 are plurilocular gametangia known, while they are knowm (or 

 reported) in the typical species of Myriodadia and Liehmamnia. There 

 seems to be represented here a distinct group agreeing in character- 

 istics of typical trichothallic apical growth and with verj^ similar mac- 

 roscopic gametophytes and sporophytes although more exact knowl- 

 edge of the types of these genera is extremely desirable, since the 

 various statements are perplexing and authentic material difficult (or 

 impossible for us) to obtain. We have made, therefore, an arrange- 

 ment of our genera and species based on the most certain information 

 available to us. It is to be borne in mind that Mesogloia (based strictly 

 on the type of the species) has been removed to the Chordariaceae 

 where it is close to, if not identical with, the genus Chordaria. Other 

 species than the type, referred by different authors to Mesogloia are 

 referred variously to Liehmannia, ^gira, Myriocladia, Myriogloia and 

 Chordaria. 



Key to the Genera 



1. Gametangia arranged unilaterally on the upper portions of the cortical filaments 

 28. .fflgira (p. 544) 



1. Gametangia not unilateral, arising from the lower portions of the cortical fila- 

 ments 29. Meneghiniella (p. 548) 



28. -ffigira Fries 



Fronds branched, filiform, with trichothallic growth, composed of 

 a medulla of colorless, branched filaments firmly agglutinated, giving 

 rise to short, cortical, assimilating filaments and to ba.sal zoosporangia, 

 or to gametangia unilaterally arranged on their outer extremities or, 

 to both zoosporangia and gametangia. 



Fries, Syst. Orbis, 1825, p. 342. Cladosiphon Kuetzing, Phyc. 

 Gen., 1843, p. 329. Castagnea Derbes and Solier, Sur les organes 

 repr. des algues, 1850, p. 269. Eudesme, J. Agardh, Till Alg. Syst. 

 II, 1880, p. 29. 



Kuetzing founded the genus Cladosiphon (1843, p. 329) on a 

 Mediterranean species, C. mediterraneus, which seems definitely, as 

 stated below, to be either the same or most certainly closely related 

 to, the species on which Derbes and Solier founded their Castagnea. 



