THE MARINE ALG.E OF NEW ENGLAND. 45 



The genus is too nearly related to CJicetomorpha, from -which it differs in substance, 

 the filaments being more or less gelatinous in Ulothrix and rigid in Chcetomorpha. Of 

 all the filamentous marine Chlorosporea the species of Ulothrix are best adapted for the 

 study of zoospores. The conjugation of zoospores in Ulothrix sonata, a fresh- water 

 species, has been very fully described by Dodel-Port in Pringsheim's Jahrbiicher, 

 Vol. X. 



IT. flacca, (Dillw.) Thuret. (Lyngbya flacca and Carmichaelii, Harv., 

 Phyc. Brit., PI. 300 and 186 a. — Hormotrichum Carmichaelii, Harv., Ner. 

 Am. Bor., Part in, p. 90.) 



Filaments fine, lubricous, greenish yellow, one to three inches long, 

 at first tufted, then entangled and forming strata of indefinite extent 

 filaments .014-30 m,n in diameter, becoming moniliform, cells .003-12 mia 

 long, generally narrow, discoidal. 



Eastport, Maine., on stones and Bhodymenia, August ; Nahant, Mass., 

 Mr. Collins, spring ; Isles of Shoals, N. H., Mrs. Davis ; Europe. 



A species most luxuriant in the spring, but also found in summer. The form found 

 at Eastport was the entangled stage which is common on wood-work at low-water 



mark. 



U. isogona, (Engl. Bot.) Thuret. (Conferva Youngana, Harv., Phyc. 

 Brit., PI. 328. — Lyngbya speciosa, 1. c, PI. 180 b. — Hormotrichum Young- 

 anum, Ker. Am. Bor., Part HI, p. 89. — Urospora penicilliformis, Aresch. 

 in part.) 



Filaments fine, yellowish green, one to three inches long, at first 

 tufted, afterwards forming strata, filaments .036-58 mm in diameter, 

 moniliform, cells .015-5Q mm long, from cuboidal becoming ovate, con- 

 striction at nodes marked. 



New York, Harvey; Ives Point, Conn., Mr. Hall; Gloucester, Mrs. 

 Davis; Kahant, Mr. Collins; Europe. Spring. 



Distinguished from the last by its greater size and by the marked constriction be- 

 tween the cells at maturity. Apparently common on wood-work. Whatever name 

 wc may give to this species, it is the same form which is common in the northern 

 part of Europe in spring and summer. It is the Hormotrichum Tounganum of British 

 authors, and the U. isogona of the French. It is the species referred by Areschoug, 

 Observationes Phycologicse, II, Act. Reg. Soc. Scient., Ser. Ill, Vol. 9, to Conferva peni- 

 cilliformis, Roth, and made by him the type of the genus Urospora. Areschoug unites 

 under the single species U. penicilliformis the following species of Phycologia Brit- 

 tanica: Lyngbya speciosa, L. Carmichaelii, L. Cutleries, L. flacca, and Conferva Youngana. 

 In the \> resent case we have kept U. flacca and U. isogona distinct, but agree with 

 Areschoug in uniting U. speciosa with U. isogona. Perhaps a further acquaintance 

 with the species might lead us to unite the present two species uuder Areschoug's 

 name. 



The Hormotrichum speciosum of Eaton's list of Eastport algae belongs to another 

 genus. The H. boreale, 1. c, is unknown to me. 



H. collabens, (Ag.) Thur.? (Conferva collabens, Harv., Phyc. Brit., 



PI. 327. — Hormotrichum collabens, Kiitz., Spec. Alg., p. 383.) 



Filaments tufted, two to six inches long deep green, cells from .05- 



