340 The American Naturalist. [April, 



ate paper on the vesuvianite crystals in the serpentine of Testa Ciarva, 

 Alathal, Piedmont, adds but little to our knowledge of these. The 

 results recorded in it but confirm Zepharovich's observations. The 

 crystals examined by the author, Striiver 1 , numbered 123, each one of 

 which was carefully measured, both as regards its dimensions and the 

 planes occurring upon it. The number of forms found on each crys- 

 tal is stated, and the number of crystals upon which each form was 

 observed is mentioned. A plate appended to the article contain.- thirty- 

 two figures, showing the arrangements of striations and the shapes of 

 elevatinii mid depres-i'. nut faces. In the sec- 



ond part ol his article on the symmetry of crystals Beckenkamp gives 

 us some exact information concerning the vicinal planes and the etched 

 figures of the aragonite of Bilin and the neighboring localities in 

 Russia, and discusses the polarity of the crystal molecule, with espe- 

 cial reference to the explanation of the electrical properties of the 

 carbonate and of its vicinal planes. The axial ratio of the aragonite 



crystals examined is .6228 : 1 : .7204. In a recent article Sohncke 3 



explains the structure of circularly polarizing crystals on the basis of 

 his point-system theory of crystal-structure. He succeeds in showing 

 that circularly polarizing crystals may be regarded as composed of 

 thin lamellae of doubly refracting substance, in which the different 

 layers are revolved a certain number of degrees around their common 



axis. Some very complicated twins of feldspar from the Pantelleria 



rocks are described by Foerstner*. They exhibit in the same group 

 combinations of all the pri - known for the species. 



The calcites of fifteen localities in Baden have undergone the 



same exhaustive examination in the hands of Sanson! 5 as have those 



of so many other well known occurrences. Miers 8 has measured the 



fourth crystal of krennerite (Au 3 Ag ;i Te 6 ) reported in mineralogical 

 literature. It is from Nagvag, Hungary, and contains six new forms, 

 viz. : 2P^, 3P^, 4P^, 2P2, 3PS and AP*. The axial ratio is 

 1.0651 : 1 : .5388. 



Miscellaneous. — Following the work of Clarke and Schneider on 

 l of the natural silicates comes the report of a series of 



