456 



THE GEOLOGIST. 



viously uubroken and in that of strata once faulted but at rest, tlie pressure 

 requisite to rupture or to fold them vn]l accumulate enormously before they 

 yield to it, ^\-heu, after some slow and gradual movements, they will be thrown 

 lip or down with a sudden movement, with or without flexures, as the case may 

 fee. Thus, by meclianical considerations, the author is led to believe that the 

 ordinary nature of movements of the earth's crust must be sudden. 



2. " On an undescribed lossil Eern from the Lower Coal-measures of jS'ova 

 Scotia." By Dr. J. W. Dawson, E.G.S. 



In a paper on the Lower Carboniferous rocks of British America, published 

 in the 15th volume of the Geological Society's Journal. Dr. Dawson noticed 

 some fragmentary plant-remains which he refeiTcd with some doubt, the one to 

 Schizopterk (Brougu.), and the other to Splmreda (L. and H.) With these 

 were fragments of a fern resembling Sphenoptens {Cli/clopteris) adiardoides of 

 Liiidley and Hutton. Since 1858 the author has received a large series of 

 better-preserved specimens from Mr. C. T. Hartt ; and from these he finds that 

 what he doubtfully termed the frond of ScJiizopteris is a flattened stipe, 

 and that the leaflets which he referred to Sphenopteris adiantoides really 

 belonged to the same plant. Mr. Hartt's specimens also show that wliat Dr. 

 Dawson tliought to be Sphccreda were attached to the subdivisions of these 

 stipes, and are the remains of fertile pinnae, borne on the lower part of the stipe, 

 as in some modern ferns. This structure is something like what obtains in 

 the Cuban Aneinua adiantlfolia, as pointed out to the author by Prof. Eaton, 

 of Yale College. No sporangia are seen in the fossil specimens. 



Dr Dawson offers some remarks on the diflBculties of arranging this fern 

 among the fossil Cj/c^npferides, Kcpggeratliia', and Adiantites ; and, placing it 

 in the genus 0/f7o^/V^'/7>, he suggests that it be recognized as a subgenus 

 (Aneimites) with the specific name Acadica. 



The regularly striated and gracefully branching stipes, terminated by groups 

 of pimnilcs on slender petioles, must have given to this fern a very elegant 

 appearance. It attained a great size. One stipe is twenty-two inches in dia- 

 meter, where it expands to luiite with the stem ; and it attains a length of 

 twenty-one inclies before it branches. The frond must have been at least tlu'ee 

 feet broad. The specimens are extremely numerous at Horton. 



The author then notices tliat the long slender leaves so common in the Coal- 

 measures of Nova Scotia, and hitlierto called Poacifes, though sometimes like 

 the stipes of A>ieimites, are prol):ibly leaves of Cordaites. 



On some specimens of Aneiinifes Acadica markings Uke those made by insects 

 have been observed ; also a specimen of the Spirorbis carbo/iarius. 



X "On the Sections of Strata ex]io*ed in the excavations for the South 

 High-level S(iwer at Dulwieh ; with Notices of the Possils found there and at 

 reekluun." By Charles Bickman, Esq. (Connnunicated by the Assistant- 

 Secretary.) 



In the autumn of 1859, open cuttings were made at Peckham, in comicxicn 

 with the " ICIlVa branch of the Great South High-level Sewer," for the "main 

 drainage" of the metropolis south of the Thames ; and in the following spring 

 u tunnel (^H:U1 \ards in length) was being constructed under the Pive-fields at 

 .Duhvieh. 'Hie beds exposed in both sections belonged to the -'"Woolwich and 

 Bending Series" of the London Tertiaries (Prestwieh). 



Pour shafts were sunk to facilitate the driving of the tunnel ; and the follovrng 

 beds were exjiosed ; but. as some of the beds not persistent, but die out 

 even with the extent of the tunnel, the several shafts diltered as to the sections 

 obtained from them. 



1. S(nl. nine inches, t?. Loamy Clay (probably London Clav) ; twelve feet. 

 Not ni shall No. 1 most easterly), uor in No. ^ (the most westerly), owing 



