THE MARINE ALG^ OF NEW ENGLAND. 45 



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

 the filaments being more or less gelatinous in Ulotlirix and rigid in Ckcetomorpha. Of 

 all the filamentous marine Chlorosporcce the species of Ulotlirix archest adapted for the 

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

 species, has been very fully described by Dodel-Port in Pringsheirn's Jahrbucher, 

 Vol. X. 



TJ. flacca, (Dillw.) Tlmret. (Lyngbya flacca and CarmicJiaclii, Harv., 

 Phyc. Brit., PL 300 arid 186 a. — Hormotrichum Carm ichaelii, Harv., Ner. 

 Am. Bor., Part III, 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 mm in diameter, becoming moniliform, cells .003-12 rara 

 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., PL 328. — Lyngbya speciosa, 1. c, PL 186 b. — Hormotrichum Young- 

 anum, Ner. Am. Bor., Part III, p. 89.— Urospora penicilliformis , Aresch. 

 in part.) 



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

 tufted, afterwards forming strata, filaments .036-5S mm in diameter, 

 moniliform, cells .015-50 mm long, from cuboidal becoming ovate, con- 

 striction at nodes marked. 



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

 Davis; Nahant, 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 

 we 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 Younganum of British 

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

 Observations Phycologica3, II, Act. Reg. Soc. Sclent., 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 present 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 under 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. 



U. 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- 



