3Iiscellanies. 359 



Leaves all petiolate, suborbicular,* obsoletely or obtuse repand, 

 dentate, and gradually diminishing in size, but preserving nearly 

 the same form, to the ends of the branches. 



Flowers small; the corollas not half the size of those of the 

 rhomboidea, and comparatively inconspicuous. 



The plant continues to extend its slender branches, fresh and green, 

 nearly all summer. They usually lie prostrate on the mud, and of- 

 ten strike root, after the manner of creeping, or radicating stems ; 

 a circumstance, I venture to say, never observed in the other spe- 

 cies. Sometimes a young shoot, or proliferous stem, starts from 

 the end of the raceme of siliques, after the fruit is full grown. 



The foregoing discriminating features of the plants in question will 

 probably be deemed sufficient ; and are submitted with considerable 

 confidence in their accuracy. W. D. 



To the Editor of the American Journal of Science. 



2. On Xanthite and its crystalline form, with a notice of Mineral 

 Localities ; by Lt. W. W. Mather, Assistant Prof, of Chem. and 

 Mm. U. S. M. A. — Xanthite has been described as a new mineral 

 species by Dr. Thomsonj from its chemical and some of its physical 

 characters. f I have now the pleasure to state, that it also differs in 

 its crystallographical characters, from any mineral species hitherto 

 described. Dr. Thomson describes it as a mineral of " a light gray- 

 ish yellow color, consisting of a congeries of very small rounded 

 grains, easily separable from each other, and not larger than small 

 grains of sand. These grains are translucent, and some of them indeed 

 transparent. The lustre of the transparent grains is splendent; that 

 of the translucent grains shining. The lustre is inclining to resinous. 

 The grains are rounded, but when examined with the microscope, 

 they seem to consist of imperfect crystals. The texture before a 

 powerful magnifier seems foliated ; but the grains are so small, that 

 it is not easy to make out its true texture with accuracy. Specific 

 gravity, 3.201. 



" Easily crushed to powder by the nail of the finger. It is there- 

 fore soft. It does not scratch calcareous spar. Infusible before the 

 blowpipe per se. Nor did it fuse along with carbonate of soda." 



* I have occasionally noticed, at the base of the larger, lower leaves, a pair ol 

 lobes, exhibiting an effort as it were to form pinnatifid leaves. 

 t Ann. of the Lye. of Nat. Hist, of New York, for April, 1S28, 



