FRESH-WATER ALG^ OF THE UNITED STATES. 209 



The ultimate branch groups are ovate or oval, and are remarkable for their open- 

 ness, the branchlets being few in number and widely separated. Most of the ulti- 

 mate branchlets are prolonged into a remarkably strong long hair. 



The cells of the main filaments are beautifully transparent, and are sometimes 

 cylindrical but more generally are barrel-shaped. Both secondary and primary 

 branches are often arranged singly, sometimes in pairs, not unfrequently in threes. 

 When placed between two plates of glass and examined closely by the unaided 

 eye, this species is readily distinguishable from our other Draparnaldia, by its fas- 

 ciculi of branches being so widely separated as to be not at all confused with one 

 another. 



I have a single specimen which I believe to be in fruit. The resting spores 

 (fig. 6, pi. 14) are in long branched chains. They are more or less globose, with 

 a very thick outer transparent wall, and an inner green endochrome, which very 

 probably becomes brownish at maturity. Except when they are branched, these 

 series of spores remind one very strongly of the filaments of some nostocs. 



I dedicate this very beautiful species to Dr. J. S. Billings, U.S.A., to whom I 

 am under the greatest obligations for aid in the prosecution of this research, and 

 whom I have ever found to unite the greatest scientific liberality with a strong en-, 

 thusiasm for and able prosecution of the. study of these lowey vegetable forms. 



Since describing this species I have received the Microscopical Journal for 1869, 

 containing Dr. Hicks's paper upon D. cruciata. The original description in the 

 Linnsean Transactions had escaped my notice. D. cruciata and D. Billingsii are 

 exceedingly closely related, yet if Dr. Hicks's description and figures be accurate 

 they are. probably distinct. Thus in the last species the ramuli are not placed at 

 right angles to the main filament, nor are they ever in fours, both of which are 

 given as characters of D. cruciata. They are, on the contrary, in D. Billingsii at 

 various angles, and commonly arise singly, but not unfrequently in pairs, and very 

 rarely in threes. It is worthy of remark, on the other hand, that the figures of 

 Dr. H. do not entirely agree with his description, as in no case are there more than 

 two and frequently but a single branch at one place. The cells of the main fila- 

 ment are also more barrel-shaped in our species than one would infer to be the 

 case with D, cruciata. 



After all, however, I think it very possible that both forms belong to the one 

 species. 



Fig. 6, pi. 14, represents a small portion of the frond with fertile branches mag- 

 nified 460 diameters. 



Genus CH^TOPHORA, Schrank. 



Fila articulata ramique primarii i-adiatim dispositi, e cellulis vegetativis elongatis, fascia chloro- 

 phyllosa in morem Draparnaldiee et Stigeoclonii ornatis compositi, sursum in ramulos numero- 

 sissimos, brevius articulates, articulis extremis attenuatis ssepe inanibus non ant vix piliferis in- 

 Btructos, fasciculatos plus minns dense congestos divisi, massa gelatinosa firma, coriacea vel dura 

 inToluti, tballum globosum vel subglobosum aut plane expansum varie lobatum et fissum con- 

 stituentes. (R.) 



Filaments articulated, with the primary branches radiately disposed, composed of elongated vege- 

 tative cells, ornamented with a chlorophyllous fascia like a Draparnaldia or Stigeoclonium, distally 



27 September, 1872. 



