498 A NATURALIST IN THE PACIFIC chap. 



border evidently favour, as he observ^es, the early decay of exposed 

 calcareous remains. 



The Slwre-plants and Stranded Seed-drift of the Panama Isthmus. 



I spent two days at Panama and two days at Colon in 

 examining the neighbouring beaches and estuaries of the Pacific 

 and Atlantic coasts of the isthmus. On the Panama side the 

 mangrove-belt was formed on the seaward border of " mangle 

 chico " (the small prevailing type of Rhizophora mangle), Lagun- 

 cularia, and Avicennia ; whilst behind it passed into extensive 

 swampy tracts occupied by the Swamp Fern (Chrysodium aureum), 

 Hibiscus tiliaceus, and other plants. On the Colon or Atlantic 

 side the mangrove-belt had precisely the same composition and 

 presented the same species, Rhizophora and Avicennia usually 

 forming the outposts on the reef-flat, whilst Laguncularia was 

 abundant in the rear. In the estuary of the Rio Chagres, 

 Rhizophora and Laguncularia were abundant near the mouth, and 

 Chrysodium aureum and Hibiscus tiliaceus by the waterside 

 higher up. Dr. Seemann, in his volume on the botany of the 

 voyage of H.M.S. Herald, observes that the species of Lagun- 

 cularia common on both the Atlantic and Pacific coasts of the 

 Panama isthmus is L. racemosa. This species differs in the form 

 of its fruit from the Ecuador tree. Laguncularia racemosa, 

 Rhizophora mangle, and I may add Anona paludosa and Cono- 

 carpus erecta, are all plants of the mangrove-formation that occur 

 not only on the Pacific and Atlantic coasts of America but also 

 on the west coast of Africa. It is likely, I may add, that the 

 " mangle grande," the Ecuadorian type of Rhizophora mangle, 

 exists in the Panama isthmus, since in the higher part of the 

 estuary of the Chagres I found trees approaching it in characters. 



Amongst the plants growing on the Panama beaches I noticed 

 Canavalia obtusifolia, Hibiscus tiliaceus, and Ipomea pes caprae, 

 all of which occur also on the Atlantic side of the isthmus. The 

 Manchiiicel (Hippomanes mancinella), found also on the Atlantic 

 side of the continent, grows on the Panama beaches. Its fruits, 

 which look like crab-apples, lose their outer fleshy covering when 

 drying on the sand. Not being familiar with this poisonous tree, 

 I allowed some of the milky sap of the fruits to touch the skin, and 

 suffered great pain for five or six hours. The fruit possesses an 

 inner coat of air-bearing cork-like tissue ; and the stone, if I 

 may so term it, thus acquires great floating power. I kept some 



