FRESH-WATER ALG^ OP THE UNITED STATES. 81 



Remarhs. — I found this plant growing in the large spring at Spring Mills in 

 March or April. The fronds were in the form of little blackish balls attached to 

 the stems of mosses in the water. They varied in size from the minutest speck, 

 scarcely visible to the naked eye, up to ten lines in diameter ; they are globose, 

 very firm and hard, and the larger look almost as if they were aggregations of 

 smaller ones. They are gregarious. The spores are mostly borne on the edges 

 of the frond, sometimes they appear to be imbedded in its substance. At first 

 they are of an intense bluish-green, but afterwards they appear to be yellowish- 

 brown. None of the cells, as I have seen them, have their contents granulate. 



Fig. 5 a, pi. 10, represents a section of a frond magnified 460 diameters; fig. 

 5 6, a section of the edge of an old frond, developing spores. 



P. hyalina, Lyngb. 



" Eronds from a quarter of an inch to an inch in diameter, somewhat globose, but at length fre- 

 quently more or less elongated into an ovate or even cylindrical form. Substance gelatinous 

 and very tender, of a pellucid, watery appearance. Granules numerous, globose, green. 

 The fronds are produced at first on rocks and stones at the bottom of streams, and afterwards 

 become disengaged and float on the surface." 



Remarhs. — Professor Bailey states that he has found this species from Khode 

 Island to Wisconsin. Whether it is identical with the P. hyalina of Brebisson, or 

 not, I cannot say. 



Genus PAGEROGALA,i Wood. 



Thallus solidus, gelatinosus, indefinitus, exalbidus, nonnihil pellucidulus, nodulis dense aggregatis 

 et saepe confluentibus formatus. Cellulae globosae, confertsB, in familias consociatae. Familiae tegu- 

 mentis tenuibus et membranaceis involutse, in nodulorum eentro pOsitae. 



Thallus solid, indefinite, gelatinous, whitish, somewhat pellucid, composed of closely aggregated 

 nodules v\?hich are often indistinct. Cells globose, crowded in families. Families surrounded by a 

 thin membranaceous coat and placed in the centra of the gelatinous nodule. 



Remarhs. — This curious plant was found by myself floating as indefinite masses 

 of milk-white jelly on a mountain spring near Bear Meadow, Centre County, Penn-; 

 sylvania. The largest of these gelatinous masses was six inches long. On taking 

 them out of the water they were seen to be composed of somewhat irregular 

 nodules, which in some portions of the mass were very distinct one from the other, 

 but in other parts were confluent into an almost uniform jelly. When the nodules 

 were separated it was discovered that each contained a membranous very delicate 

 sack of a pale green color, which the- microscope showed to be really a cell family. 

 Their interior was hollow, or at least only partially filled with a transparent fluid, 

 and they contained all round their exterior portion a layer of round, closely placed 

 cells. In some instances the outer membrane was ruptured, and the sac only con- 

 tained a few cells, which could often be seen to be moving freely in the inner 

 liquid. The sac membrane is thin and delicate, colorless, and marked with curious, 

 regular wrinkles or folds. In those portions of the common gelatinous mass, where 

 the nodules were lost, I could not find any of these sacs. 



' Iloiytpoj, frozen ; ya?ia, milk. 

 11 May, 1872. 



