152 Miscellaneous, 



6. "On Fuchsia, considered morphologically," by the Rev. Dr. 

 M'Cosh. 



The branches of the species selected are whorled in threes, as are 

 also the leaves. The normal angle of the branches is about 60°, that 

 of the leaf also 60°. 



I now endeavoured to find whether the curve of the branchlets and 

 the curve of the vein corresponded. This I found to be difficult ; but it 

 occurred to me to try and find the law of the ordinates of the curves, 

 and the result shows that the ordinates increase by equal increments 

 in equal spaces, and that the increment is = to the abscess. This was 

 the law of the curve of the branches and of the veins of the leaves. 



7. " On Monstrosities of the Dandelion and common Clover ob- 

 served near Turin," by Charles Murchison, M.D., British Embassv, 

 Turin. 



8. " On the Flora of Bonn, on the Rhine," by G. S. Blackie. 

 Mr. Blackie observed, during his three months' stay in the neigh- 

 bourhood of Bonn : — 



Dicotyledones 586 species. 



Monocotyledones 175 „ 



Acotyledones 28 „ 



Total number of species. . 789 



9. "Microscopical Observations on a kind of Paper made from 

 Vegetable Tissue," by John Matthews. Mr. Matthews had exa- 

 mined the specimen of paper presented at the last meeting of the So- 

 ciety, and found that it exhibited beautiful cells with stomata. It was, 

 therefore, the cuticle of a plant, and from the quadrangular stomata 

 he was disposed to think that it was allied to Agave. 



Dr. Seller was elected President for the ensuing year. 



MISCELLANEOUS. 



Observations on the genus Acostsea of D' Orhigny. 

 By J. E. Gray, F.R.S., V.P.Z.S. &c. 



M. D'Orbigny, in the * Revue et Magazin de Zoologie' for 1851, 

 pp. 60 & 185, t. 3. describes a new freshwater Bivalve discovered by 

 Col. Acosta in New Grenada, under the name of Acostcea ; the 

 following is an abridgement of his characters : — 



" The young shell is free, equivalve, inequilateral, thin, closed ; the 

 ligament elongate, convex ; the interior, like Anodontce, with two 

 muscular scars ; characters determined by the elongate form of the 

 shell. In the intermediate age, while enlarging, the shell suddenly 

 leaves its regular form, being till now free. It lies on its side, the right 

 valve below, which moulds itself upon the body which it touches, 

 extends itself on the substance and fixes itself there. The ligament 

 remains on the side of the valves. The left valve now becomes the 

 upper one, and commences to open itself at the anal region ; it then 



