14 Mr. T, Smith on certain Species of 



to expect graceful foiins where stiffness is essential. Pleasing 

 forms are not however to be altogether despised, provided 

 they be consistent with fitness ; and I think it will be found 

 that straight-lined figures combined so as to indicate that in- 

 flexible stiffness and solidity which we natiu'ally expect in an 

 instrument intended to measure with accuracy the relative di- 

 stances of such distant objects, will not be wanting in power 

 to call forth some of those pleasing sensations usually compre- 

 hended under the common term of Beauty. 

 [To be continued.] 



VI. On certain Species of CaxduvLS and Cmcus xvhich appear 

 to be dicecious. By Thomas Smith, Esq. F.R.S. Sf L.S.* 



A LTHOUGH Linnaeus founded his orders in the class 

 -^ *- Sijngeiiesia upon nice distinctions, drawn from the various 

 modes in which the florets of different sexes are arranged in 

 each capitulum, the fact that many species were dioecious, or 

 Iiad the male and female flowers on distinct plants, almost en- 

 tirely escaped his observation ; for in the last edition of his 

 Genera Plantanim, published in 1764, he remarks, that Gna- 

 2>haliitm dioicum is a rare example of the separation of the sexes 

 ui this class. 



Jussieu in his Genera Plant arum, published in 1789, does 

 not appear to have been aware of any other example than the 

 above, for he observes at the end of his generic character of 

 G uapliarnim, " Species una dioica insigni exceptione." 



It has however been pointed out to me by my friend Mr. 

 Brown, that at the time this observation of Jussieu's was 

 published, Friedrick Ehrhart had shown that some species of 

 Tussilago were dioecious : and our native species Tussilago 

 hybrida and Petasites now rank as one only under the name 

 of Petasites, which is the male, hybrida being the femalef . 



Mr. Brown in his Observations on the Compositcc, inserted 

 in the 12th volume of the Transactions of this Society, an- 

 nounced many more instances of this remarkable circum- 



* From the Transactions of the Linnacan Society for 1822. Part II. 



■j- Vide Friedrick Eh.rhart Be'ilrage zur Naturlininde, vol. iii. 17H8. Tlie 

 paper is however dated December 1783, and had previously been printed 

 (I believe) in the Hanovci' Magazine, probably about the latter date. 



It may be proper nevertheless to note, that M. Cassini, whose extended 

 and accurate investigation of this class gives great weight to his opinion, has 

 come to an opposite conclusion to the above, and considers the two plants 

 as distinct species. His words are: " Les styles du Tiissi/ngn /;j/6/7(/« dif- 

 ferent assez du ceux du T. Petasites, pour demontrcr, inde|)endaninient dc 

 plusieurs autres nrguniens, que ces deux plantes n'appartiennent point a la 

 memc cspece, commel'ont cru trcs mal-a-propos ijuelrjues botuiiistcs mo- 

 derncs." — /utthual dc r/ii/sirjue, toni. Ixxvi. p. 191. 



stance: 



