OF THE UNITED STATES. 179 



Length of the aperture 1 5 of an inch. 



Greatest breadth somewhat less. 



Inhabits the River Delaware. 



This species seems to be rather rare ; it was dis- 

 covered by Mr. Aaron Stone, deeply imbedded in 

 the mud ; Mi\ William Hyde of this city, has since 

 found specimens of it, amongst some dead shells of 

 other genera assembled in a small inlet of the river. 



Descriptions of rare plants recently introduced into 

 the gardens of Philadelphia. By Thomas Nut- 

 tall. Read March 5, 1822. 



* NEMOPHILA.f 



Calix decemfidus, laciniis exterioribus reflexis* 

 Corolla subcampanulata quinquelobata, lobis emar- 

 ginatis, ad basin foveolis marginatis staminiferis. 

 Stamina brevia, filamentis nudis. Capsula carnosa 

 unilocularis bivalvis. Semina quatuor. 



Herba succulenta annua, caule triquetro ; foliis al- 

 ternis pinnatifidis, pedunculi longissimi uniflori op- 

 positifolii et terminali subracemosi, racemis incurvis, 

 fructibus defiexis. Corolla sastivatione convoluta. 

 HydrophyUum affinis. 



N. Phacelioides. 



Description. Root fibrous annual, but more 

 commonly biennial. Stem fragile, smooth, some 



t From 7i/a«c, a grove, and 0»m«» I l»ve, a plant peculiar to 

 shady woods 



