1854.] Linnean Society. 347 



Planchon among the number, as merely an epidermis of the testa ; 

 but it becomes difficult to discriminate between a very thin arillus and 

 a thick epidermis, as both appear to be of the same nature, varying in 

 degree of thickness from one extreme to the other in different genera of 

 that family. The most instructive and conclusive evidence of the origin 

 and subsequent extraneous grovpth of the arillus over the ovule, has 

 been adduced by Cambessfedes, who found in Casearia many incom- 

 plete seeds where the anatropal ovule remained in a state of com- 

 plete abortion, while the arillus had grown over it to its full extent, 

 proving that where the ovule had ceased to grow, the increment of 

 the funiculus was not stopped in its progress of extraneous develop- 

 ment. According to the hypothesis of Dr. Planchon, the outer 

 tegument in the ClusiacecB, as well as in the Magnoliacece, must be 

 a true arillus. 



The facts thus demonstrated will, Mr. Miers argues, necessarily 

 change our views of the affinities of the Clusiacea, serving to bring 

 the order into close proximity with the Rhizobolacece, a relationship 

 long ago pointed out by Cambessedes, founded upon their floral 

 structure, but now rendered more evident by the great similarity 

 observable in their extraordinary embryonal development. The 

 latter family exhibits likewise an embryo with a gigantic radicle, 

 and exceedingly small cotyledons, but here these are separated from 

 the radicular body by a slender free caulicle or neck ; now if we 

 imagine the suppression of this caulicular extension, and the close 

 approximation of the minute cotyledons to its monstrous radicle, 

 there would be little or no diiference in the structure of the embryo 

 in the two families. While these circumstances tend also to draw 

 closer the affinity of the Clusiacea to the Hypericacea and Marc- 

 graaviacecB, they tend to remove them far from the Ternstrcemiacece, 

 with which order they have been hitherto considered to be most 

 intimately related. The farther consideration of the real affinities 

 of the Clusiaceee will be more fully examined by the author, who 

 intends on a future occasion to treat of the organography, floral 

 structure, and generic features of the whole family, restricted within 

 the limits be proposes. 



December 5th, 1854. 

 William Yarrell, Esq., V.P., in the Chair. 

 Mr. Ward, F.L.S., exhibited two sets of specimens of Asplenhim 



