17 



11. C. Tasmanica, Nobis. 



12. C. Dnimmondii, Benth. et Hook. f. 



13. C. Roei, Endl. 



14. C. Morrisoni, R. T. Baker. 



15. C. Muellen, Benth. et Hook. f. 



16. C. ohlonga, Rich. 



17. C. Macleayana, Benth. et Hook. f. 



18. C. sp. nov., Nobis. Not placed. 



It was expected that a number of varieties would have been found 

 amongst these species, extending as they do over very wide geographical areas, 

 but such is not the case, and no genus could have less varietal forms, or more 

 well-defined species than Callitris. But in this connection it must not be 

 forgotten that this ^^ide geographical area does not present in some instances 

 great en^■ironmental differences, a correlation, so to speak, of circumstances which 

 no doubt accounts for uniformity or constancy of species of the genus — a character 

 also common to our Eucalypts, as shown in the " Research on the Eucalypts and 

 their Essential Oils." A status quo extending over an enormous period of time 

 probably produces such a constancy. 



Excluded Species. 



The following species are given in the " Index Kewensis," Fas. I. 389, as 

 Australian species, but as no literature or material of them appears to be extant, 

 or at least in any of the herbaria visited by us, and as Heynhold only gave names, 

 they may be regarded as nomena nuda, and so have been excluded from 

 this work. 



C. conglobata, Sieber ex Heynh. Nom. i, 148. There is a seedling speci- 

 men in the Brussels Herbarium, labelled " C. conglohata, Herb. 

 Martii. 1826." It is too immature for systematic placing. 



C. elegans, Sieber ex Heynh. Nom. i, 149. 



C. montana, Sieber ex Heynh. Nom. i, 149. 



III. THE ARRANGEMENT OF THE CALL/TRIS SPECIES IN 



ORDER OF SEQUENCE. 



In working out the taxonomy of the species of this genus, advantage was 

 taken to employ the aid, where possible, of the several cognate branches of 

 science in order to establish a classification founded as near as possible on a 

 natural basis, and thus not relying alone on one special set of characters or features. 



In this particular instance, morphology, chemistry, ecology, physics, and 

 anatomy were laid under tribute, and the result is given in the table below. 

 B 



