552 University of California Puhlications in Botany [Vol. 8 



FAMILY 13. CHNOOSPOEACEAE fam. nov. 



Fronds elongated, solid, slender, more or less compressed, more or 

 less regularly dichotomous or proliferous from the margins, growth 

 subapical, not triehothallic, of two sets of tissues, an inner of large 

 cells, an outer of one or more layers of small colored cells in short 

 anticlinal rows ; hairs in clusters arising from the bottoms of shallow 

 pits ("cryptostomata") ; zoosporangia unknown; gametangia uni- 

 seriate, arising about the clusters of hairs and spreading over the 

 surface, at times into confluent sori. 



The genus Chnoospora is usually ranked as of uncertain position 

 ("incertae sedis"), but by some placed in the Encoeliaceae, a family 

 now abandoned and with its members distributed and separated. In 

 its sori, surrounding the hair clusters, it resembles closely those of 

 Colpomenia, but in habit and terminal growth it is very different from 

 that genus and its near relatives. The frond is not directly to be com- 

 pared with that of any brown alga at present known to us. The slender, 

 compressed and regularly dichotomous frond at once sets it apart. The 

 subapical method of terminal growth relates it more nearly to Hetero- 

 chordaria, but Chnoospora is known only with gametangia as are the 

 members of the Scytosiphonaceae. The method of subterminal growth 

 is like that of the genus Stilophora, but it is very different from that 

 genus in not having free cortical filaments. Chnoospora may be con- 

 sidered to be a further development of the cylindrical Scytosiphon- 

 aceae, with the loss of the terminal hair and the growth in length 

 localized. It certainly seems best, at present, to place Chnoospora in 

 a family of its own. 



The structure and the fructification were first described by Ethel 

 Sara Barton (1897). Borgesen (1924, p. 264) calls attention to the 

 resemblance of the growth point to those of Scytothamnus australis 

 and Coilodesme hulligera. Both of these plants probably are to be 

 referred to the Chordariales since they possess only zoosporangia of a 

 distinct unilocular type and it is to be suspected that they have 

 microscopic gametophytes. 



31. Chnoospora J. Ag, 



Fronds cylindrico-compressed, solid, ecostate, profusely branched, 

 attached by a solid holdfast ; branching dichotomous, f astigiate ; fronds 

 differentiated into two tissues, the center of larger, colorless prismatic 

 cells, elongated longitudinally, surrounded by tw^o layers of small cells 



