ANNOTATIONS AND ADDITIONS. 153 



Casuarinas with their leafless, thin, string-like, articulated 

 branches, having the joints provided with membranous den- 

 ticulated sheaths, have been compared by travellers, accord- 

 ing to the particular species which fell under their observa- 

 tion, either to arborescent Equisetaceae (Horsetails) or to 

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

 Near the coast of Peru the aspect of small thickets of Col- 

 letia 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 unknown in India and on 

 the east coast of Africa. 



( 23 ) p. 25." Needle-leaved trees." 



The family of Coniferse 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 (Dam- 

 mara, Ephedra, and Gnetum, of Java and New Guinea) . The 

 number of known Coniferse is not quite equal to three-fourths 

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

 more known Aroidese than Coniferse. Zuccarini, in his 

 Beitragen zur Morphologic der Coniferen (Abhandl. der 

 mathein. physikal. Classe der Akademie der Wiss. zu Mlin- 

 chen, Bd. iii. S. 752, 1837-1843), reckons 216 species, 



