1920] Seichell-Gardner : Chlorophyceae 241 



Desmazieres, Plantes Crypt, de France, 3 Ser., no. 603, 1859; 

 Collins, Green Alg. N. A., 1909, p. 212 ; Setchell and Gardner, Alg. 

 N.W. Amer., 1903, p. 207. Ulva quaternaria Kuetzing, Tab. Pliyc, 

 vol. 6, 1856, p. 6, pi. 13, f. 2. 



Monostrmiia quaternarium resembles M. latissimum in habit and 

 habitat. Both are usually found in either brackish or fresh water 

 and are not strictly marine. Both are usually found floating and 

 are more or less indefinitely expanded. In M. qu-aternarium the cells 

 are rounded, segregated in small groups of three or four in surface 

 view, while in M. laUssimum the cells are angular and closely placed, 

 although at times appearing somewhat grouped. It is by no means 

 a certain matter to place some specimens definitely in one species 

 or the other. Such a case is presented by no. 218 of Farlow, Anderson 

 and Eaton's Algae Americae Borealis Exsiccatae, collected near Santa 

 Cruz, California, probably in an estuary. 



6. Monostroma latissimum (Kuetz.) Wittr. 



Frond at first attached, afterwards floating; thin and soft, glossy, 

 of irregular shape, more or less plicate near the even or undulate 

 margin; membrane 20-25/a thick, cells 4—6 cornered or roundish, 

 closely set, without order or more or less distinctly in twos, threes and 

 fours ; in cross section vertically oval or nearly circular, 14-18/a liigh. 



Attached to various objects in the lower littoral belt when young, 

 but soon becoming free and floating in quiet waters, salt marshes, 

 ditches, etc. Washington to central California. 



Wittrock, Monostr., 1866, p. 33, pi. 1, f. 4; Collins, Green Alg. 

 N. A., 1909, p. 211; Setchell and Gardner, Alg. N.W. Amer., 1903, 

 p. 207. Viva laUssima Kuetzing, Phyc. Gen., 1843, p. 296, pi. 20, f. 4. 



As stated under the preceding species, Monostroma latissimum is 

 usually to be found floating in shallow warmer waters, either brackish 

 or fresh, seldom, if ever, in true marine localities. It is to be dis- 

 tinguished from the last {M. quaternarium) by the appearance of 

 the cells both in surface view and in section as indicated in the 

 descriptions. 



The propriety of adopting the specific name latissimum for this 

 species may be questioned. It seems to be the Viva latissima of Kuetz- 

 ing, but probably not the Viva latissima of Linnaeus. We are not in 

 a position to discuss this question, and simply follow later usage. 



