128 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lv, 



Listera ovata, Orchis foliosa, Onosma tauricum, Oxytropis 

 campestris, 0. Hallcri, Potcntilla criocarpa, Primula sik- 

 Jcimensis, Bamondia pyrenaica, Styliclium gramini-folium, 

 Silene pusilla, WahlbcrgcMa ixiucifiora, Xanthosia rotundi- 

 folia, Saxifraga hroncJiialis, S. tnutata, and S. lingulata 

 seedling. 



Presents to the Library, Museum, and Herbarium at the 

 Eoyal Botanic Gardens were announced. 



The following papers were read : — 



The Pilgomayo Expedition : Pkeliminary Notice. By 

 J. Graham Kerr, Naturalist to the Expedition. 



In this preliminary communication I shall confine myself 

 to giving a short sketch of the Expedition itself, along with 

 a summary of the more striking botanical features of the 

 region traversed by it. 



A considerable portion of the Southern part of South 

 America is occupied by an immense plain, Avhich stretches 

 from the uplands of Brazil, Entre Kios, and Paraguay on 

 the East, up to the base of the Cordilleras of the Andes on 

 the West ; and from Patagonia and the Atlantic on the 

 South, up into the inner provinces of Bolivia upon the 

 North. The Southern part of this plain — that adjacent to 

 Buenos Aires and the Bio de la Plato — is well known to all 

 as the Pampas ; while its more Northern portion forms the 

 much less known, and still to a great extent unexplored, 

 region of the Gran Chaco. These two regions are sharply 

 marked of!" from one another by a striking difference in their 

 vegetation. The Pampas is characterised by the almost 

 absolute absence of trees of any kind ; the Gran Chaco is 

 characterised, on the other hand, by the very great develop- 

 ment of arborescent forms both of Dicotyledons and Palms 

 which there cover large extents of country. 



Traversing the Gran Chaco from West to East are 

 several rivers, of which three are of importance — the Salado, 

 the Bermejo, and the Pilcomayo, all alike taking their origin 

 among the snows of the Andes, and traversing the Chaco in 

 a south-easterly direction to join the Paraguay -Pa ran a river 



