560 Notices of Memoirs — /. Hophinson on Graptolites. 



mixture in the cubic form. The action of acid on maskelynite 

 pointed to its composite nature, to the possibility of its consisting of 

 an aluminous silicate containing soda which is less readily acted 

 upon than another aluminous silicate containing lime. 



Tschermak represents the Sherhgotty meteorite as made up of : 











Total 



Total 





Pyroxene. 



Maskelynite. 



Magnetite. 



Composition 

 (Calculated). 



Composition 

 (Observed). 



Silicic acid 



38-51 



12-68 







50-89 



50-21 



Alumina 



0-18 



5-79 







5-97 



590 



Iron protoxide 



16 93 







■ 



16-93 



17-59 



Magnesia 



. 10-43 











10-43 



10-00 



Lime 



. 765 



2-60 







10-25 



10-41 



Soda ... . 



,, 



1-14 







1-14 



1-28 



Potash ... . 



. 



0-29 







0-29 



0-57 



Magnetite 



. 







4-50 



4-50 



4-57 





73-40 



22-50 



4-50 



100-40 



100-53 



Specific gravity 



... 3-466 



2-65 



5-0 



3285 



3-277 



While the Sherghotty stone by its peculiar constitution defies in a 

 way proper classification, it finds a place among the small group of 

 eukritic meteorites, and resembles most closely that of Petersburg 

 (1855, August 5th). 



Found 1866. — Frankfort, Franklin Co., Kentucky. 

 [Lat. 38° 14' N. ; Long. 80° 40' W.] x 



This block of meteoric iron, which was found on a hill 8 miles 

 S.W. of Frankfort, was conveyed to a blacksmith's forge in that 

 town, in order to test its quality as iron. It weighs .24 lbs., has a 

 somewhat globular form and a highly crystalline structure. The 

 specific gravity of this iron is 7-692 and the composition.: 



Iron = 90-58 ; Nickel = 8-53 ; Cobalt = 0-36 ; Phosphorus = 0-05 ; Copper, 

 trace. Total = 99-52. 



(To be concluded in our next Number.) 



1TOTICES OIF HVCIEIMIOIIR-S. 



Paper Read before the British Association at Bristol, August, 1875, 

 Section C. Geology. 



J, — On the Distribution of the Graptolites in the Lower 

 Ludlow Eocks, near Ludlow. By John Hopkinson, F.L.S., 

 F.G.S. 



f~nHE author first drew attention to the special interest attaching 

 I to the Ludlow Eocks, in connexion with investigations on the 

 vertical distribution of the Graptolites, as being the formation in 

 which they apparently die out. 



The Ehabdophora or true graptolites, which with the Cladophora 

 or dendroid forms, are found in infinite variety when they first ap- 

 pear in the Arenig rocks, genera the most complex coming-in simul- 

 taneously with simpler forms, were stated to be represented in the 

 Lower Ludlow rocks by but a single genus, Monograptus ; and the 

 Cladophora also by one genus only, Ptilograjptus. 



1 J. L. Smith. Amer. Jour. Sc, 1870, xlix. 331. 



