94 Mr. Brown's Observations on the 



that it is more analogous to the outer calyx of Scabiosa, which 

 M. Cassini seems to consider cliflcrent in its nature from both 

 these parts. 



But the order of expansion in Lagasca, which is, though with 

 some degree of irregularity, from centre to circumference, or 

 that of the compound capilulum, seems to decide the question 

 respecting the envelope of each flower, and to establish its iden- 

 tity with involucrum : nor does tlris involucrum differ materially 

 from that of £c///«oyw, except in the reduced number and con- 

 fluence of its component parts. 



The real structure of Casulia is perhaps less obvious. 



This genus, which was first published by Dr. Roxburgh*, is 

 referred by him to Polygamia segregata ; the tubular envelope or 

 involucrum of each floret beina; described as distinct from the in- 

 eluded ovarium. 



Koenig, on the other hand, by whom the genus was discovered, 

 and whose account of it is given in the same work, describes the 

 partial involucrum of Roxburgh as the surface of the ovarium 

 itself; its segments being, according to him, a pappus of two 

 leaves. And lastly Willdenow, regarding this involucrum as merely 

 paleae of the receptacle, refers the genus to Polygamia ajqualis ; 

 in which order it is continued, both in Persoon's Synopsis, and in 

 the second edition of Mr. Alton's Hortus Kewensis. 



This last view of the structure seems the most erroneous of any, 

 and was probably adopted by Wdldenow, in consequence of his 

 having added to the genus a second species not really belonging 

 to it, and which I shall have occasion to notice in another part 

 of my subject. 



An examination of the parts of fructification in different stages 



* In Corom. Plants, i. p. 64. t, 93. 



reconciles 



