NEW YORK STATE MUSEUM 
LIST OF DOUBTFUL OR UNCERTAIN FORMS (continued) 
NAUMANN BRAVAIS-MILLER 
SYMBOL SYMBOL 
—iRis 3.10.13.6 
— i R20 13.27.40. 12 
—15R3% 12.25.37.11 
— 6Ri3 10.16.26.5 
— 28R13 12.40.52. 23 
—5R2 8,132, 4 
—19R94 17.74,.91.45 
S=ERS 4.8.12.3 
—iRs. 7.35.42.20 
—1iRis 11.62.73. 36 
—3Ri4 7.61.68.36 
RE 2572 
—sRo 5.13.18.5 
—8R3 8.16.24.5 
— FR25 2.23.25. 12 
—16R3 4.20.24.7 
—19R 89 16.73.89.27 
— 25 R24 1.26.27.9 
—3R13 rie 1346 
—88R25 6.44.50.7 
6R2 Dusmlon 
—8R5 16.24.40.1 
Re erieeaea 
—14R? 2.16.18.1 
—15R1it il tent 
—29R3t 180.300. i 
—66R33 2.68.70. 1 
—161R23 7.168.175.1 
LOCALITY AUTHOR 
Andreas ero mmr ait SR ne Sansoni 
Andreas erent errr Sansoni 
INNCHTEAS NTs ab vlad atioooudaee Cesaro 
AUMNOMEASIOCCY, o gan ocscradeo ge Sansoni 
Blatoneig ih .-epe cae tae ee Sansoni | 
Blatonan waa trae cnG Cesaro $ 
ERMA cucte ee RC RR eT vom Rath 
Rigi SNe sre dare Gis clea tener: Cesaro 
Bergen ually er tac 2 ger Dana 
LOE eee AA canna ie SUA eas vom Rath 
By Silva ics bade ke cha eb eee RAR esto oO Zippe 
Cumberland ra see eee Bournon 
FR eee ae MEMO ai Src Des Cloizeaux 
IRISMES a pyar: nace ORE Ie Cesaro 
Pooee a rsa eS) Pata ters cuneate Biche Obs 6 Des Cloizeaux 
Bnuglande een ee Schaller 
Mamcashirevy. = 34x. rin cen vom Rath 
RISMES Aes ie reas Mien) pe ween Cesaro 
RiRISNES Seite. eee Gare eee Cesaro 
UNMET AG Tes Fine De ni eeereory Cage Des Cloizeaux 
Ket ara Ean te Pier ER SAA Ate Des Cloizeaux 
ANNCKAS OOTY“ ooccc cosa edses Hessenberg 
AMENGOAS OSG wow ousdedsoc5 4% Sansoni 
Inhodesisland irr etrieier Schaller 
ANACHEASOCY 5559400000008 0¢ Sansoni 
ANISCOM WOOK 655 oe0dsoc0000. Des Cloizeaux 
NSO. WOOP. 5 5.456 occcG0 ds Cesaro 
BUSTOR WOOP. 5 50h oo sooo as os Zippe 
Twinning. Composite crystals, in which two or more parts are united 
in reversed position according to definite crystallographic laws of orienta- 
tion are known as twin crystals and the laws which govern their formation 
are known as twinning laws. 
The species calcite is characterized by twin 
crystals formed in accordance with four laws distinguished by the position 
of the twinning plane, that is to say the plane of juncture between the 
composite elements of the twin crystal. 
the order of their frequency they may be briefly stated as follows: 
Taking these four twinning laws in 
