W. A. E. Ussher — Subdivisions of the Trias. 163 



1-1 6th of an inch. The colour of the interior is a bluish-white and 

 is very uniform. More than half the stone is made up. of rounded 

 grains of the size of mustard-seed, with fine-grained white or 

 greyish-white interstitial matter, which Shepard calls chladnite, but 

 which would perhaps now be more correctly termed enstatite. The 

 rounded globules are bluish-grey, rarely with a- faint tinge of yellow, 

 are vitreous and translucent, have two imperfect oblique cleavages, 

 and bear a resemblance to boltonite. Minute grains of iron are 

 thickly scattered through the mass, with a few grains of troilite and 

 one little black mass, which was probably graphite. The specific 

 gravity of the stone is 3-626 — 3-701. Dr. Lawrence Smith traces a 

 great resemblance, as regards the crust, between this stone and that 

 which fell at Mauerkirchen (1768, November 20th) ; but both 

 observers agree that in other respects, more especially in spherular 

 structure, it is like the meteorite of Aussun (1858, December 9th). 

 It is to be regretted that the constituents of this stone, which can 

 apparently be so readily isolated, have not been subjected to separate 

 analysis. 



The total composition of the stone is as follows- : — 



Olivine 4304 



Bronzite, hornblende, with a little albite (or orthoclase) and chromite 3927 



Nickel-iron 14-63 



Magnetic pyrites (?) 3-06 



The nickel-iron consists of: 100-00 



Iron = 90-02 ; Nickel = 9-05 ; Cobalt = 0-43 = 99-5 



and the stony portions, soluble and insoluble in acid (and alkali), 



amounting respectively to 52-3 per cent, and 47-7 per cent., have the 



following composition : 



Si0 2 Alo0 3 FeO MgO Alkalies Fe 7 S 8 



A. Soluble 40-61 .". 19-21 36-34 ... 3-06 = 99-22 



^.Insoluble 56-25 2-01 13-02 24-14 2'10 ... = 97'52' 



(To be continued in our next Number.) 



III. — On the Subdivisions of the Triassic Bocks, between the 



Coast of West Somerset and the South Coast of Devon. 



By W. A. E. Ussher, F.G.S., 



Geological Survey of England and "Waks.. 



MUCH has been written on the relations of the Devonshire Trias 

 as observed in the south-coast section. The subject itself is 

 associated with many names of high scientific repute, so that, were 

 the following epitome the result of partial examination, or in any 

 way aided by preconceived notions arrived at from the perusal of the 

 labours of those who have gone before, I should not feel justified in 

 differing in many points from men infinitely my superiors in general 

 geological information. But after a careful survey of these rocks, 

 extending over three years, beginning in the Vale of Taunton, without 

 any jnevious acquaintance with the series, and working from dark 

 to light, my views altering as to their mode of occurrence, as I pro- 

 ceeded southwards, till the same divisions were established 



