FRESH-WATER ALG^ OF THE UNITED STATES. 183 



Syn.—U. merismopedioides, Wood, Botanical Report of the United States Geological Ex- 

 ploration of the Fortieth Parallel, p. 415. 



J3a6.— In torrentibus, Diamond Range (alt. 6000 ft.). Rocky Mountains ; (Sereno Watson) Wood. 



Thallus ample, broadly expanded, membranaceous, dilute green, thin, radiately and irregularly 

 plicate with its outline often somewhat rounded ; its margin undulate or at times almost 

 crenate; the cells irregularly oval or angular, destitute of nucleus, quarternary and obscurely 

 arranged in families after the manner of a merismopedia. 



Bemarhs. — The largest fronds of this species that have come under my notice 

 are about three inches long by two broad, thin, easily torn, and not all gelatinous. 

 The portion by which they have been attached is very evident, near one of the 

 margins, and from it broad undulations or folds radiate. Sometimes the frond is 

 split up into palmate, lobe-like parts. 



The cells are not closely approximate, but are placed in a homogeneous translucent 

 membrane, in such a way as to remind one of a Merismopedia. 



I do not feel certain that this plant is distinct from U. orhiculata of Rabenhorst, 

 though for the present I have preferred so to consider it. His description is very 

 brief and incomplete, as is also the original one of Thuret, which I have con- 

 sulted. Prof B,., however, gives U. latissima of authors as a synonym of U. or- 

 hiculata, and certainly this plant is distinct from U. latissima, Harvey, of our 

 coast. Again it seems impossible that a plant growing near the summit of the 

 Rocky Mountains should be identical with one found on the coast of France. 

 Prof, Sereno Watson found this plant growing on rocks in a mountain stream of 

 the Diamond Range, at an altitude of 6000 feet. 



Genus ENTEROMORPHA, Link. 



Thallus membranaceus, tubulosus vel utriculiformis, basf affixus (saltem initio, postea ssepe libere 

 natans), e cellularum strato unico compositus, S83pe ramosus, haud raro ramosissimus. Propogatio 

 fit zoogonidiis. Hsec zoogonidia proceantur in cellulis quibusdam 8-16 eytioplasraatis divisione 

 repetita, in polo antico rostriformi ciliis duobus corpus duplo superantibus prsedita. (R.) 



Thallus membranaceous, tubular or bladder-shaped^ affixed by the base (at least in the beginning, 

 often afterwards floating freely), composed of a single stratum of cells, often branched, not rarely 

 very much branched. Propagation by means of zoospores, 8-16 of which are formed by the 

 repeated division of the protoplasm of a cell. Their anterior beak-like portion provided with two 

 cilia whose length is not less than twice that of the body. 



E. intestinalis, (Linn.) Link. 



E. teres, forma et magnitudine admodum varia, sffipe pedalis etiam supra, leptoderma, saturate 



vel pallida viridis, filiformis vel intestiniformis, plana vel bullosa ; cellulis 3-5-6 angularibus. 



(R.) Species mihi ignota. 

 J>zam.— 0.00048" — 0.0008". (R.) 

 Syn. — E. intestinalis, (LiNN^iEUs) Bailey, Silliman's Journal, N. S., Vol. III., et Rabenhorst, 



Flora Burop. Algarum, Sect. III. p. 312. 



Hah. Hudson River, from Newburgh to New York City ; Narragansett Bay, Rhode 



Island; Bailey. 

 Terete, very various in size and shape, often a foot or more in length, smooth, deep or pale 



green, filiform or intestiniform, plain or bullose ; cells 3-5-6 angular; their diameter 0.00048' 



— 0.0008". 



