24 DF.sMIDs OF THE INl'IKD STATES. 



Frequent in ponds of New Jersey, Pennsylvania, etc. 

 There are two forms very Dearly allied, this //. undulata, and 

 Sphaerozosma excavatum (Ralfs,) both about the same thick- 

 ness and same length of cell, and both in a colorless gelatin- 

 ous envelope ; the only point of separation is in the attach- 

 ment of the cells ; in the Hyalotheca the cells adhere by 

 the whole plane of the end, and in the Sphaerozosma, they 

 are connected by two sessile glands on the margin. To my 

 mind this distinction is scarcely tenable. 



II. dubia, Kg. Plate I, tig. 14. 



('ells about as long as wide, not constricted, closely united 

 into short fragile filaments, without gelatinous -heath. 

 Diameter 1 32 1 />. 



This form occur- DOW and then in waters of ponds in New 

 Jersey. As the name implies, it holds a somewhat dubious 

 position. It is without the mucous envelope characteristic of 

 the other species ami i- usually smaller. Fruiting B|>ecimena 

 have not Keen observed. 



Reasoning from observations on the life history of an allied 

 genus, Bambusina, I venture to BUggesI that the forms re- 

 ferred to this Bpecies, are merely undeveloped conditions of 

 other Bpecies. 



Genus, BAMBUS1 \ A. Kg. 

 Plate L figs. 15-24. 



( lells "f joints barrel-shaped, surrounded by one or two narrow 

 median bands, closely united into articulate, nodose filaments. 

 Chlorophyl bodies and zygospores as in Hyalotheca. 



I'). Brebissonii, Kg. /'. Borrerif Cleve; Didymoprium Borreri, 

 Balfa.) Plate I. figs. 15-21. 

 ('ells somewhat longer than broad, hub or. barrel-shaped, 

 surrounded in the middle with two narrow bands, and another 



often visible between these and the ends <>!' the cells. 

 Diameter 1 *-_>:, ,,. 



Frequent in quiel water- from .Maim t - Florida ami far 

 west. A.*pond at Pleasant Mills. New Jersey, furnished me 



with good condition- of development. The lowest traceable 



Btage is represented by fig. 17. A gelatinous -heath enclos- 

 ing a series of green cells; iig. 18, four cells around which 



