264 APPENDIX. 



In Southern Mexico, in the Isthmus of Tehuantepec, according to Barrosa *, Quercus 

 virens begins at about 100 metres above the level of the sea, and in the central part 

 associated with a pine it covers large areas. 



We have eighteen species of Quercus recorded from Guatemala, where, as in Mexico, 

 oak-forests constitute one of the most important elements of the vegetation. Thus in 

 the western mountains (Volcan de Fuego) the chief forest above the tropical zone 

 consists of evergreen oaks succeeded by pines f. 



Although we have only one species of Quercus noted as Nicaraguan, there is ample 

 evidence of the existence of oak-forests in various parts of Nicaragua J, and the genus 

 is probably not less strongly represented than it is in Costa Rica, where some ten 

 species are known to exist, nine of which are also natives of either Mexico or 

 Guatemala, or both. Finally, Seemann collected three species on the Volcan de 

 Chiriqui. Two of these have been described as species not found elsewhere, while 

 the third has been identified with one also recorded from Guatemala. The region 

 of oaks, alder, and Agave americana in Chiriqui is fixed by Moritz Wagner § at from 

 4200 feet to 8000 feet; and here as in Mexico the oaks are associated with palms 

 (Chamcedorea) up to an altitude of 7000 feet. 



Much more might be said concerning the distribution of the oaks of Mexico and 

 Central America, but it must suffice to repeat the important facts of their almost total 

 absence from the West Indies, their great rarity in the Andes, where they do not 

 extend southward to the equator, and the richness and abundance of endemic forms 

 within our limits. 



Lacistemacece. 



Lacistema is a genus of shrubby and arboreous plants restricted to the New World, 

 and so distinct in character that it cannot well be treated otherwise than as an inde- 

 pendent natural order, the position of which in a linear arrangement is not easily 

 settled. There are about sixteen species spread all over tropical America including 

 the West Indies, but chiefly in Brazil and Guiana. Only one species (L. myricoides, 

 Sw.) has been found in Mexico and Central America ; this is spread throughout the 

 West Indies, and covers nearly the whole area of the order in South America. 

 Furthermore it is the only species known to grow in the West Indies. 



The Coniferous Vegetation. 

 Five out of six of the tribes of Coniferae adopted in Bentham and Hooker's ' Genera 



* "Apuntes sobre la Yegetacion del Istmo de Tehuantepec," Anales del Ministerio del Pomento de la 

 Kepubliea Mexicana, iii. (1880) pp. 309-330. 



f O. Salvin, " Der Yolcan de Fuego in Guatemala/' Petermann's Geographische Mittheilungen, 1861, p. 395. 



% Pirn aud Seemann, ' Dottings in Panama and Nicaragua,' passim. 



§ Petermann's ' Geographische Mittheilungen,' 1863, p. 294. Agave americana should probably be Furcrcea 

 gigantea. 



