36 



thickly charged with glauconite. Professors Bonney and Seelcy 

 have SLiggesLeil that the red colouring matter (peroxide of iron) 

 of the red chalk of Hunstanton was derived from decomposition 

 of glauconite. (The question of the probabilities of the glau- 

 conite having been decomposed after or during the deposition 

 of the rock, was discussed.) The author of the present paper 

 had, while examining sections of the Hunstanton Rock under 

 the microscope, discovered that certain facts (which he now 

 detailed) which led him to consider the opinion of Professors 

 Bonney and Seeley was in a high degree probable. 



Specimens were shown of Haematite. Specular Iron, Glau- 

 conite, Glauconite altered by heat, Hunstanton Rock, Bognor 

 Rock, and Cambridge Greensand : diagrams of Cystosoma 

 Neptuni and .(Eglina binodosa and microscopic slides of Hun- 

 stanton Rock, Cambridge Glauconite marl, and Glauconitic chalk 

 from Antrim were exhibited to illustrate the paper. A series of 

 slides illustrating the decomposition of Olivine to form Serpen- 

 tine was also shown, and Prof. Bonney's description of the 

 process was read. 



PAPER BY DR. DONALD BAYNES, M.A., F.R.G.S., ON 

 THE COCA SHRUB. 



May 5th, 1880. 



Dr. Donald Baynes, M.A., F.R.G.S., said: — The Coca shrub 

 belongs to the order of Erythro.xylaceos (sapindales.) There are 

 several species, some of them yielding useful products, as for 

 example : — Erythro.xylon suberosum, from which is obtained a 

 brownish dye. The young branches and leaves of the Erythroxy- 

 lon areolatum are said to be cooling, and when mixed with benne 

 oil form a refreshing liniment for the head. The bark is also 

 used as a tonic. (Ainslie ii. 422.) The bark of the Erythroxylon 

 anguifugum, is thought to be an antidote against snake-bites in 

 Brazil. 



But, the Erythroxylon coca, so called from the Indian 

 " Khoka," signifying a tree, or plant, is by far the most important 

 plant of this order. It is a shrub from 5 to 20 feet in height. 

 The leaves are a delicate bright green, lighter on the under 

 surface, usually smooth, alternate, and from 1 to 3 inches in 

 length. The distinguishing characteristic of the leaf is, how- 

 ever, two arched lines, one on either side of the midrib, which 

 meet at each extremity ; these marks or lines are caused by the 

 folding of the leaf in the bud. The flowers are small, whiteish 

 or greenish, and the fruit is a one-seeded, oblong berry, about 

 the size of a pea. 



This plant is found wild, and is cultivated in several of the 

 South American States, notably in Peru, Bolivia, Equador, and 

 Brazil, &c. The leaves are the part used, either chewed, or 

 taken in the form of infusion as tea. The gathering, curing and 



