330 PHYSIOGNOMY OF PLANTS. 



and Tasmania (Van Dienien Island). Casuarinas with their leafless, 

 thin, string-like, articulated branches, having the joints provided 

 with membranous denticulated sheaths, have been compared by tra- 

 vellers, according to the particular species which fell under their 

 observation, either to arborescent Equisetacese (Horsetails) or to our 

 Scotch firs. (See Darwin, Journal of Researches, p. 449.) Near 

 the coast of Peru the aspect of small thickets of Colletia and Ephedra 

 also produced on my mind a singular impression of leaflessness. 

 Casuarina quadrivalvis advances, according to Labillardiere, to 43 

 S. lat. in Tasmania. The sad-looking Casuarina form is not un- 

 known in India and on the east coast of Africa. 



(a*) p. 242. " Needle-leaved trees." 



The family of Coniferae holds so important a place by the number 

 of individuals, by their geographical distribution, and by the vast 

 tracts of country in the northern temperate zone covered with trees 

 of the same species living in society, that we are almost surprised at 

 the small number of species of which it consists even including 

 members which belong to it in essential respects, but deviate from 

 it in a degree by the shape of their leaves and their manner of 

 growth (Dammara, Ephedra, and Gnetum, of Java and New Guinea). 

 The number of known Coniferae is not quite equal to three-fourths 

 of the number of described species of palms ; and there are more 

 known Aroideae than Coniferae. Zucearini, in his Beitragen zur 

 Morphologic der Coniferen (Abhandl. der mathem. physikal. Classe 

 der Akademie der Wiss. zu Miinchen, bd. iii. -s. 752, 1837-1843), 

 reckons 216 species, of which 165 belong to the Northern and 51 to 

 the Southern Hemisphere. Since my researches, these proportionate 

 numbers must be modified, as, including the species of Pinus, Ci*- 

 pressus, Ephedra, and Podocarpus, found by Bonpland and myself 

 in the tropical parts of Peru, Quito, New Granada, and Mexico, the 

 number of species between the tropics- rises to 42. The most recent 

 and excellent work of Endlicher, Synopsis Coniferarum, 1847, con- 

 tains 312 species now living, and 178 fossil species found in the 

 coal measures, the bunter-sandstone, the keuper, and the Jurassic 

 formations. The vegetation of the Ancient World offers to us more 

 particularly forms which, by their simultaneous affinity with several 



