170 Ulothricaceae 



larger size and shorter cells. Judging from all specimens we have 

 seen, it is more distinct from the latter than is M. Loefgrenii. In 

 the Central Park station, where we have observed it at several dif- 

 ferent seasons, it shows a very constant character, and is never 

 mixed with any other Microspora. There it is usually found with 

 Cladophora and Rhizocloniutn, in a stream gushing from and over 

 rocky ledges to feed the lower lake. 



In other cases, where it has been found in connection with M. 

 amoena (588) and M. Loefgrenii (632), no intergrading forms have 

 been seen, and there has been no evidence of any developmental 

 relationship. 



In two specimens of the exsiccata above quoted, nothing but 

 M. amoena has been found, but Professor Wille's forma crassioris 

 based on this material. His characterization of the form consists 

 only of a statement of the diameter of the cells (without any refer- 

 ence to synonyms), but judging from this point alone the form is 

 to be included here. 



2. Microspora amoena (Kutz.) Rabenh. Flor. Eur. Alg. 3: 321. 



1868. Lagerh. Ber. Deutsch. bot. Gesell. 5: 417. 1887. 



DeToni, Syll. Alg. 1: 227. 1889. Kirchn. Mik. Pflanz. 12. 



pi. 2. f. 26. 1 89 1. Hansg. Prod. Alg. Bohm. 2 : 222. 1892. 



De Wild. Flor. Alg. Belg. 46. 1896. 



Conferva amoena Kutz. Spec. Alg. 372. 1849; Tab. Phyc. 

 3 : pi. 4.5. f. 5. 1852. Kirchn. Krypt. Flor. Schles. 2 1 : 79. 1878. 

 Wille, Ofvers. Vet. Akad. Forhand. 1881 8 : 21. //. 10. f. 57. 

 1881. Hansg. Prod. Alg. B6hm. I: 77. 1886. Wolle, F. W. 

 Alg. 140. pi. 121. f. 1-5. 1887. 



Filaments forming long green skeins or tangled masses ; cells 

 nearly cylindrical, often slightly contracted at the dissepiments, 

 21.5-25 /i in diameter, 1-2 times as long ; cell-wall 2.5-3 P thick ; 

 chromatophore rather dense, generally covering the cell-wall and 

 obscuring the nucleus which is 6.5-7.5 fi in diameter (//. 2j t /. 1). 



Exsic: Phyc. Bor. Am. 616, p. p., Bridgeport, Conn., April, 

 1893 (I. Holden) ; ipB (as Ulothrix zonatd), Melrose, Mass., 

 April, 1894 (F. S. Collins) ; Tild. Am. Alg. ijpA (as M.floccosd), 

 Forest Grove, Oregon, Feb., 1896 (F. E. Lloyd). 



In brooks, streaming in masses from sticks and stones on 

 which it is caught. 



