150 MB. J. BALL ON THE BOTANY 



Payta lies about five degrees south of the equator, very near 

 the northern limit of the so-called rainless zone, but within less 

 tluin 100 miles of places on the southern side of the Gulf of 

 Guayaquil which are described as within the region of tropical 

 rains, and as possessing the characteristic vegetation of the 

 Equatorial zone. Eain to an appreciable amount had not fiillen for 

 three years before the date of my visit, and the immediate 

 vicinity of the port apjieared to the eye absolutely devoid of 

 vegetation. Assisted by several fellow-travellers, who were kind 

 enoiigh to join in the search, I think it probable tljat I col- 

 lected every plant then to be found within a radius of more than 

 a mile from the town on the plateau about 100 feet above the 

 sea, which in most places approaclies close to the shore. My 

 collection contains only the following 12 species : 



Tephrosta cineuea, Pers. A stunted form of this widely 

 difiused species is found in many parts of tropical America, and 

 extends southward to Monte Video and Buenos Ayres. It is 

 wrongly described as an annual in Persoou's ' Enchiridion ' and in 

 DcCandolle's ' Prodromus.' It has a woody rootstock, sometimes 

 an inch in thickness, and the branches are often woody at the 

 base. TejyJirosia Utoralis, Pers., and T. procumlens, Macf , are 

 scarcely distinguishable even as varieties, and several other 

 described species approach very near, both in structure and 

 appearance. 



IIooJc. et Am. Bot. Misc 



I believe tliat this species is confined to North Peru. It is true 

 that specimens were distributed by Cuming with the label 

 " Panama et Colombia occidentalis ; " but there is reason to 

 apprehend that the labels to Cuming's eoJlectious were affixed 

 without any close regard to topographical accuracy *. The genus 

 extends from the southern border of the region which I propose 

 naming Argentaria, chiefiy along the west side of the continent, to 

 New Mexico, and thence eastward to Texas, and, like many other 

 genera mainly American, has two representatives in South Africa. 



Pbosopis limensis, Benth. in UooJc. Journ. Bot. iv. p. 350, 



forma sphwsa. This appears to be a characteristic plant of the 



rainless zone of Peru, but I have not seen specimens from any 



seem 



collected oa the west coast of tropical America, between 18° or 20° S. lat. and 

 10° N. lat.-either that above quoted or " Lima et Peruvia septentrionalis." 



