70 Botanical Society of Edinburgh. 



rotundd, intus rufd, ad basim angulatd^ labro repando, rufo- 

 marginato ; columelld incrassatd. 

 Hab. Marshy places. Vera Cruz, Mexico. 

 Length '8, diam. '3 of an inch. 



Remarks. — Neither of the four specimens under examination are 

 perfect, all being much eroded at the apex. Under the microscope 

 the surface may be observed to be papillose, a character rarely found 

 in this genus, though not very uncommon in Helix. The aperture is 

 rather more than one-third the length of the shell and is unusually 

 rotund. The rufous line surrounds the peritreme. The aperture is 

 reddish inside. 



[To be continued.] 



BOTANICAL SOCIETY OF EDINBURGH. 



Thursday, 13th Nov., 1851.— Prof. Balfour, President, in the Chair. 



The following papers were read : — 



1. "On the Gulf Weed (Sargassum bacci/erum),'^ by Mr. Samuel 

 Mossman. 



This was a lecture giving an account of all that is known on the 

 subject of the Gulf Weed and Sargasso Sea, and professedly contained 

 little or no original information. We have therefore thought that an 

 abstract would unnecessarily occupy space. 



2. "On the Correspondence between the Angles formed by the 

 Veins of the Leaves, and those formed by the Branches of the Stem," 

 by Mr. WiUiam Mitchell. Communicated by the Rev. Dr. M'Cosh. 



Having been informed that the Rev. Dr. M'Cosh had thrown out 

 the idea that a plant, considered morphologically, may be regarded as 

 a unity ; and, in proof of this view, had produced many examples 

 among forest trees, pointing to the similarity of the ramification 

 of the branches and the venation of the leaves, the general cor- 

 respondence of the angles in both, and the agreement of the 

 form of the leaf, or leafage from one point, with that of the 

 whole tree, I felt inclined to test the truth of the theory, so far as I 

 was able, by its application to herbaceous plants. For this purpose 

 I examined a great number of these plants, and found the results, 

 generally, the same as those given in the following list, which contains 

 a few of the most carefully measured of our common wild flowers : — 



Tanacetum vulgare — The angle which the branches make with the 

 stem is 45 deg. ; and it is equal to that which the side veins of the 

 leaf make with the central vein. Li the other examples we shall 

 express the two equal angles by the term "normal angle." 



Euphrasia officinalis — Normal angle, 45 deg. average. 



Scabiosa succisa — N. A., 40 deg. upper branches and veins; 35 

 deg. lower veins and root-leaves. 



Centaurea nigra — N. A., ^^ deg. average. 



Fumaria officinalis — N. A., 60 deg. 



Spircea ulmaria — N. A., 35 deg. ; terminal branches and veins 

 somewhat less. 



Senecio vulgaris — N. A., 30 deg. 



Gentiana campestris — N. A., about 20 deg. 



