Land-SlttUs of the Xatunn Islam/s, 4o7 



11. Patula persculpta. (PI. XVI. fijrg. 6-6 ^'O 



Testa orbicularis, lale umliilicata, niinuta, tiiiuis, sordidc alliida, 

 fltriis concontricis t-t s[tiralibus microscopicc oaiUfUata ; aiifraclus 

 yj, U'lite crosceiites, convexi, sutiua prot'uiula sejuiicti, ultiiuus ad 

 pcriphcriam rotiuidatiis, baud doscendens ; apcrtura parva, oblique 

 lunata ; peristoma t^'iiue, simjilex, marline culumellari vix 

 reriexo ; spira depressa, supra anfr. idtimum vix elata. 



Diam. l-o millim., alt. -75. 



Ilab. Bunguran. 



Under the niicroscopc tlie minute canccllatiou ot" the surface 

 is extremely pretty. 



12. Amphidromus perversusj Linn. 



J/(ib. Bunguran and Sirliassen. 



Several forms of this variable shell occur in the Natunu 

 collection. They may be thus described : — 



1. Entirely white, generally with one or more oblique 



brown stripes or varices. 



2. White below the suture in the last two whorls, closely 



striped beneath with rich brown, often pinkish towards 

 the apex. 



3. Yellow, but with a broad white zone below the suture, 



with or without one or two oblique brown varices 

 { = leucoxanthuSj Martens). 



The above varieties from Bunguran arc not always sharply 

 defined, but intermediates occur between one or other of them. 

 For instance, some examples have so much brown about them 

 that they cannot be included in var. 1, yet they are not suffi- 

 ciently coloured to come into var. 2. Sometimes specimens 

 of var. 2 have a somewhat yellowisli tint like var. 3, and the 

 latter occasionally has more or less of brown striping upon 

 the lower part of the penultimate and last whorls, as in var. 2. 

 The latter variety is very like the form inelanonwia, Pfr. 

 None of the Natuna examples appear to have the apex so 

 dark as that species and none exhibit a yellowish peripherial 

 zone ; but not unfrequently there is a more or less defined 

 submedian broad band as in the var. inversus, Miiller. 



4. Obliquely striped with dark brown upon a paler ground, 



darker below the sharply defined periphery { = tnversuSj 

 Miiller). 



All the above varieties from the Natunas are represented 



