486 A NATURALIST IN THE PACIFIC chap. 



understand that this is the opinion of Dr. Wolff, the historic- 

 geographer of Ecuador — that in the course of ages the tendenc}' 

 will be towards an extension of the dry, sterile regions of Northern 

 Peru into Ecuador. This subject is referred to again in a later 

 page of this chapter. 



Whilst in this neighbourhood I made the ascent for some 

 fifteen miles of the Santa Rosa River, which opens into the sea 

 near Puerto Bolivar. It is a tidal estuary that has no proportion 

 in size to the small river that enters it. In its lower third we 

 passed at first between long mangrove-islands formed almost 

 entirely, as viewed from the boat, of the tall Rhizophora trees 

 draped with Tillandsias, and presenting really a magnificent 

 spectacle. In the middle third we were penetrating into the 

 rear of the mangrove-belt. The giant swamp-fern (Chrysodium 

 aureum) abounded, and here and there we passed by a patch 

 entirely held by the large shrubs of Salicornia peruviana. The tall 

 Rhizophora trees were replaced by the short variety, the " mangle 

 chico," which ceased altogether about ten miles from the mouth of 

 the estuary, but probably only about five miles from the nearest 

 part of the coast. The water at the place where the Rhizophora 

 trees ceased was evidently quite fresh during nine out of the twelve 

 hours, being only salt in the latter part of the rising tide. Above 

 the mangroves, in the upper third of the ascent. Hibiscus tiliaceus, 

 with Chrysodium aureum, flourished on the banks. The shallows 

 at the margins were occupied by a considerable variety of semi- 

 aquatic and other plants, such as Pontederia (two species) ; one of 

 the Alismacex, with the flower and fruit of Sagittaria and the 

 leaves of Alisma ; Typha, Polygonum, and an Amaryllid like 

 Crinum. Plants of Pistia and Pontederia floated in the stream. 



I have said enough to give a general idea of the composition of 

 the mangrove-belt of the Ecuador littoral, and will refer but briefly 

 to the mangroves and other river-side plants in the neighbourhood 

 of the city of Guayaquil, some forty miles up the Guayas estuary. 

 As I have remarked in Note 38, the water of the river off the city is 

 usually quite fresh except at high water ; but the sea has much freer 

 access to the channels at the back of Guayaquil, where at high 

 water the density was 1014. In these channels are displayed the 

 typical mangrove formation, trees of Rhizophora mangle bordering 

 the water, whilst behind they are mingled with Avicennia tomen- 

 tosa and Laguncularia. On the banks of the main river, where 

 they are overflowed at high water, Anona paludosa was the most 

 frequent tree, being associated with the Rhizophora, Hibiscus 



