30 DESMTDS OF THE rTNITED STATES. 



S. vertebratuMj (Breb.), Ralfs. Plate I\\ fig. 13. 



Cells about half as long as broad with a <I<t|i narrow con- 

 striction, connected in the centre by a simple, rather thick 

 gland; more or less remote. Semi-cells narrow, elliptic, smooth. 

 Filaments twisted, usually surrounded by a mucous sheath. 



Diameter 1 2-1 1 u. 



Rather rare; the best specimens found were from Splitrock 

 Pond, Busses < lo., Nem Jersey. 



S. SERRATUM, Bailej . Plate I V. fig. 7. 



( 'ells broader than long, deeplv notched, or divided into two 

 transverse portions with acute, spinelike projecting ends which 

 give a serrated outline to the chain. Cells eloselv united !>v 

 two short glandular processes. I "-ualU surrounded lv a wide 

 gelatinous sheath. 



Diameter 'I'l 33 ". including the projections. 



Prof. Bailey collected this species in South Carolina, 

 Georgia, and Florida, 1848; it is found frequently in New 

 Jersey, Pennsylvania and other northern States. 



According to Wallich this species should ! classed with 

 Onychonema, a new genua made by him to take in such 

 -|>ii - forme as v < rratum. 



The glandular processes conn< cting the cells are sometimes 

 long, nearly equal to the length of a semi-cell; in thi> con- 

 dition it approaches very near to Onychonema laeve, Nord., a 

 Brazil form. The specimens vary considerably, Imi they 

 I" nol seem to admit of separation. The cells are often only 

 slightly inflated, sides nearly straight ; ihe Bpines, in young 



c lition nearly obsolete, or very Bmall and straight, and the 



glandular processes sometimes -hurt, barely discernable, and 

 again so long that they lap over the cells. 



S. Wai j.achii ? Jacobeen. Plate [V, fig. 15. 



A peculiar form of which I found only two -hurt 

 g})ecimen8 in pond, Brown's Mills, N. J. They arc not 

 identical with the form described l>v Jacobsen. I record the 

 figures of them provisional h until other specimens may be 

 found to verify a good species. 



Diameter 10-12 u. 



