i62 Records of the Indicvi Mtiseitin. [Vol. XIII, 



Millimefi'es. Respective Ratios. 



Trincomalie ( ^^^ 55X39 =ioo to 85-94 to 60-94 



( M io8a2 a /^" X 53i X 36ri- = 1 00 to 89- 1 7 to 60-83 



~' 1595X50^x33 —100 to 84-87 to 55-46 



Tavoy (M. 398) 49x42^x31! =100 to 86-73 to 63-78 



Bombay (\I. 10836 21 554X47^X31^ =100 to 85-52 to 56-56 



No. 4788 iitt si/fi.) =100 to 89-71 to 62-50 



Avera<)^e of ratios =100 to 86-99 '" 60-01 



(d) Variety aurora, var. nov.. 

 (Plate IV, figs. 9-11.) 



This is a strongly marked colour variety which rises to the 

 importance of a local race in Malabar in the estuaries of the An- 

 jarkandi and Tellicherry rivers, Tellicherry. The colouring con- 

 sists of continuous bands of varying width and number radiating 

 from the umbo to the ventral margin. The primitive number of 

 these radial bands appears to have been two, as this agrees with 

 the number of vestigial bands seen in other varieties of M. niere- 

 trix as well as in certain varieties of M . casta ; also because the 

 banding system in many shells can be resolved into two band 

 groups representing the two original bands. In such (figs. 9 & 10) 

 the two original bands become very wide as they approach the ventral 

 margin, and in addition a number of narrow non-widening rays 

 are intercalated in the space between the two great rays. From 

 this well-defined pattern we pass to shells where the whole surface 

 is covered with closely set rays. The colotir of the latter is dark 

 purplish brown when the periostracum is present, otherwise it is 

 duller and more livid in tint. Internally these shells are yellow- 

 ish beyond the pallial line ; within this they have a pale pinkish 

 tinge when quite fresh. Like so many other coloured shells, all 

 the species of Meretrix fade considerably with time and expo- 

 sure to light and this must be allowed for when examining shells 

 from an old collection. Sometimes young individuals of var. 

 morphina show a suffused pinkish tinge in the substance of the 

 shell and it is probably from such a stock that aurora has been 

 derived. 



Occasionally a broadly-rayed large specimen of M. casta var. 

 ovum shows raying and a general superficial resemblance to aurora^ 

 but the absence of a pink colour within, the acuter posterior angle 

 and the absence of a bifid anterior cardinal tooth in the left valve 

 are clearly-cut distinguishing differences. 



The largest of the Tellicherry specimens is 55 mm. long by 49 

 mm. deep ; the majority average 44x39X26^^ mm., equivalent to 

 the ratios of 100 to 88*64 to 6o'23. 



{e) Variety zonaria (Lamarck). 



1835. Cytliei'ea zonnria, Lamarck, Aiiiin. sans. Vert., 2nd ed., Vol. VI, 



p. 299. 

 ,, ., gvaphica, Lamarck, ibid., p. 300. 



1864. ,, ,, Reeve, Conch. Icon., XIV, Cytherea, pi. i, fig. i. 



