134- Mr, W. S. MacLeay on the Dying Struggle 



stood, than laborious descriptions of a thousand words. The 

 former at once defines the species ; but the latter distract by 

 detailing the most insensible variations. 



I remain, Gentlemen, very respectfully, 



your old correspondent, 

 Chelsea, May 1, 1830. A. H. Haworth. 



Postscript. — Please to notice the following errata, &c. 



For " Cotyledones 2, parvae," in my last communication, 

 vol. viii. p. 106, 1. 28, read " Cotyledones nullae." For I have 

 just seen two germinating species of Mammillaria without any. 



In page 107, line 1 1, for " Cotyledones nullae," read " Coty- 

 ledones duae.*' For I have also very lately perceived two very 

 minute apical ones, on an apparent species of Cereus. And 

 on mongrels purposely raised between Cereus speciosissimus 

 and Epiphyllum Phyllanthoides, I have likewise very recently 

 found two apical conspicuous connate and cordato-ovate fleshy 

 Cotyledons; and have preserved the whole in spirits. 



In my communication for October 1825, page 177, 1. 32, 

 for " frequens" read " sequens" ; for 

 September 1 829, p. 302, 1. 20, for " erectus" read " erecta ;" 

 February 1830, p. 108, 1. last but one, after " reptantibus " 



add " ramis ;" 

 February 1830, p. 114, 1. last but one, for " plantis" read 

 " plantae". 



To the above may be usefully added, that DeCandolle found 

 two very minute basal Cotyledons on Melocactus communis, 

 and two small apical ones on his Echinocactus cornigerus. 

 And hence Echinocactus becomes a subgenus only. 



A. H. H. 



XX. On the Dying Struggle of the Dichotomous System. By 

 W. S. MacLeay, Esq. M.A. F.L.S. In a Letter to N. A. 

 Vigors, Esq. F.R.S. 



[Continued from p. 57-] 



I~\R. FLEMING, however, has other and equally powerful 

 ■"-' reasons for disputing the law of continuity in the construc- 

 tion of organized matter. Because some planets in our system 

 have moons, and others not; because Saturn has a ring, and 

 because nearly one-half of the comets move from west to east; 

 therefore there is no transition from one form of organized 

 matter to the other. Q. E. D. So also, " If we arrange the 

 elementary bodies of which this globe is composed in a table, 

 according to their saturating power or atomic value, the eye 

 will not fail to perceive a series of coincidences or starts, more 



or 



