Mr. Hopkins on the Stratification of Derbyshire, 121 



and inclosing a firm and longitudinal fibre, or rather a bun- 

 dle of longitudinal fibres united into one cord, like the fila- 

 ments that compose the nerves of animals, and which termi- 

 nate ultimately in soft, bibulous, and club-shaped appendages 

 designated by the appellation of spongiolce. 



Thus we trace in plants the foundation of three grand orders, 

 depending upon the relative simplicity or complexity of the 

 structure of the caudex, and presumed to exhaust the subject. 

 They agree in point of number, but not in point of specific 

 extent, with the arrangements of modern botanists, by which 

 plants are reduced to three grand orders depending upon the 

 structure of their seeds — the acotyledonous, the monocoty- 

 ledonous, and the dicotyledonous. Whether or not these 

 groupings of threes give any support to Professor Burnett's 

 system of triads, I am not able to say ; but what we learn, 

 unequivocally, from the foregoing investigation is, that the 

 decomposite organs of all plants, to whatever division be- 

 longing, are reducible to one or other of the following con- 

 stituent parts — epidermis, pulp, pith, cortical layers, ligneous 

 layers, fibre— to the analysis of which we now proceed. 

 [To be continued.] 



XX. Bemarks on Farey's Account of the Stratification of the 

 Limestone District of Derbyshire. By W. Hopkins, Esq., 

 M.A.,Mathematical Lecturer of St.Peter' sCoUegc,Cambridge, 

 and Fellow of the Geological and Cambridge Philosophical 

 Societies. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 AM R. CONYBEARE, in the latter part of his " Inquiry how 

 ■*-*•*- far De Beaumont's theory is applicable to the mountain 

 chains of this country," which appeared in the Number of the 

 Philosophical Magazine for June, in speaking of the elevated 

 chain of hills which ranges N. and S. through our northern 

 counties, has expressed considerable doubts as to the accuracy 

 of Farey's account of the geology of the limestone district of 

 Derbyshire, which forms the southern extremity of the chain ; 

 and this I observe has led you to refer, in a note, to an abs- 

 tract, published in the Phil. Mag. for January, of an account 

 which I laid before the Cambridge Philosophical Society of 

 an investigation I had recently made of one or two important 

 points in the stratification* of that county. During the spring 

 of the present year I have had an opportunity of extending 

 my investigation over the greater part of the district; and as 



Third Series. Vol. 5. No. 26. Aug. 1834. R 



