.53 



SANTALACE^E. 



1S4. Comandra pallida D. C. Near the Great Bend of 

 Heart River, June 24th. Met with but a few times. 



EUPHORBIACE.E. 



185. Euphorbia dyctiosperma Fisch. & Moq. Near cross- 

 ing of the Little Missouri, July 11th. 



186. Euphorbia marginata Pursh. Abundant in the val- 

 ley of the Yellowstone at the mouth of Custer's Creek, and thence 

 up the Yellowstone to Pompey's Pillar. Confined mainly to the 

 bottom-land of the Yellowstone, and not seen below Custer's Creek. 



187. Euphorbia montana Engl. Near the crossing of the 

 Little Missouri, July 11th. 



188. Euphorbia polygonifolia Linn. Shell Point, Yel- 

 lowstone River, July 19th. 



189. Euphorbia serpens H. B. K. Shell Point, Yellow- 

 stone River, July 19th. 



URTICACE^E. 



190. Ulrnus fulva Michx. Common along Heart River, and 

 other small streams between the Missouri and the Yellowstone. 



191. Humulus Lupulus Linn. Occasional along the wooded 

 parts of all the streams. 



CUPULTFER^E. 



192. [? Quercus maerocarpa Michx.] A species of Quercus, 

 probably Q. maerocarpa, occurs abundantly at a few localities on 

 Heart River, thickly clothing the dry ravines, or coulees, that extend 

 back from the river, where they form sometimes almost the only tree 

 occurring at these localities. It was not noticed west of the Little 

 Missouri. 



SALICACE^. 



193. Salix nigra Marsh. Common along the streams. 



194. Salix longifolia Muhl. Common along the streams. 



195. Populus monolifsra Ait. Abundant along all the 

 streams, at some localities constituting the only timber met with. 

 Alone the Yellowstone, above Tongue River, and also on the Mussel- 



