124 PITTONIA. 
D. RHoMBOIDEA. Arabis rhomboidea, Pers. Syn. ii. 204. 
Cardamine rhomboidea, DC. Syst. ii. 246. C. bulbosa, B. S. P. 
Prel. Cat. N. Y. 4. Thisspecies has been supposed to be iden- 
tical with the Arabis foliis ovatis denticulatis glabris of Grono- 
vius, and therefore to be the Arabis bulbosa of Schreber. 
Dut as there is nothing in either the name or the synonyms of 
Gronovius to indicate what plant was intended, A. bulbosa, 
Schreb., is a nomen nudum. Not a description which I can 
find, anterior to Persoon, would lead any one to even this 
group of plants. He is the first to mention rhomboid leaves 
and a tuberous root; characters by which the botanist is led | 
at once to these tuberous-rooted Dentarias notwithstanding 
that they are misleadingly placed under Arabis by the author. 
D. ROTUNDIFOLIA. Cardamine rotundifolia, Michx. Fl. ii. 
30. This I consider rather more likely to be the plant called 
Arabis bulbosa by Schreber and Muhlenberg than the pre- 
ceding, my reason being the geographical one. The diag- 
nosis given in Michaux is almost too brief and deficient to 
save the name. 
D. Dovarassm. Arabis Douglassii, Torr. in T. & G. Thi 
88, as a synonym under C. rotundifolia. Cardamine Doug- 
lassii, Britton, Trans. N. Y. Acad. ix. 8. A beautiful, and | 
perfectly distinct species, as I learned to recognize it in the 
middle Mississippi Valley thirty years ago. 
2. A proposed new genus, SCHOENOCRAMBE. 
The plants to which I desire to assign the above generic 
name were first brought imperfectly to the knowledge x 
botanists, from the northern part of the Rocky Mountain 
region, by Douglas and by Wyeth. The specimens collected 
by Douglas were mistaken by Sir William Hooker for those 
of a species which had for some time been known from the 
steppes of Siberia and northeastern Europe, a plant which 
