1817] NEW GENERA OF PLANTS. Ill 



very close affinity to each other; both are accounted good 

 foodi and attain to about the same size. 



In the early part of the present month, I procured seve- 

 ral individuals of the C. macrolepidotus, in the markets 

 of Philadelphia; they had not the dorsal fin hollowed, but 

 it was raised in a point before, and truncated in a very ob- 

 lique line, which diminished the fin towards its posterior 

 part. One of these specimens was a male, and it did not 

 differ in other respects from the specimen described, No. 

 4 of this article, which I omitted to mention was a fe- 

 male. This additional notice is necessary, in order to 

 put the naturalist on his guard when he turns his observa- 

 tion on this species. 



An account of two new genera of Plants^ and of a species of 

 TiLLiEA and Limosella, recently discovered on the 

 banks of the Delaware^ in the vicinity of Philadelphia. 

 By Thomas NuttalL Read September 16, 1817. 



In July last, while collecting specimens, near Kensing- 

 ton, of the Isoctes lacustris w^hich grows so abundantly on 

 the mirey and gravelly banks of the Delaware, subjected 

 to the flowing of the tide, I happened, almost inadvertent- 

 ly, to discover a very small succulent plant, somewhat re- 

 sembling a Sedum, which on examination, proved to be 

 a species of TilUa, I at first, as well as my friend Mr. 

 Collins, supposed it to be the T. connata of the Flora Pe- 

 ruviana, but on examining the plate, and description in that 



