he Monthly Microscopical Journai, Sep^l. I87i. 



Pl.XCV. 



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o< 



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Redb Or. Yel CJ 



Reai OroLn^e Yellow Greert BLllc IncLuijo 



HedL OyaunAjfe Yellow G-r&erv SLu^ InaUqo 



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Tu/fen.West sc W.WestA C u,ip 



Spectj'a by polarised li^^hi llirou^.h doubly- 

 i^efractinp cpysiaJs. 



