AN ISLAND IN THE CHILKA LAKE. 



267 



triangular processes separated by an interval slightly greater than the width of that 

 part of the whorl that lies above them. There are about seven processes in each 

 series, the upper of which is sometimes obsolete except for a single process on the 

 lip. They vary somewhat in size and direction, but those of the upper row are always 

 pointed upwards and slightly outwards. The whole surface of the whorl, including 

 that of the processes, is covered with spiral ridges interrupted by longitudinal grooves 

 in such a way that a chequered pattern is formed. Towards the base of the shell one 

 (or sometimes two) of the ridges is usually prominent and below it a deep broad, 

 oblique transverse hollow is formed. The siphonal notch is relatively long and visible 

 from above. 



The mouth of the shell is a little oblique, narrowly oval, produced above into a 

 well-defined vertical notch and below into the siphonal process. Outside the former it 

 sends a channel obliquely outwards into the last triangular process of the upper row. 

 The outer lip is rather sharp, finely crinkled and crenulate or almost smooth. Ihe 





A. 

 Text-fig. 2. — vShells of Cuma dispmcta, sp. nov. (nat. size). 



A. Type-specimen from the Andamans. 



B. Fresh specimen from the Chilka Lake. 



columella is straight, vertical and sharply pointed, its callus coarse and procellaneous. 

 Beyond the callus the shell is narrowly rimate and beyond the chink its base is orna- 

 mented with numerous curved and sinuate grooves and ridges. 



Measurements (in millimetres) of Shells. 







Type (I) 



(2) 



(3) 



(4) 





(5) 



(6) 



(7) 



Height 





42-5 



.38-3 



35-0 



40-6 





40 



i8-8 



5-0 



Max. diam. 





33-4 



27'2 



27-0 



30-0 





27-2 



13-5 



3-5 



Height of mouth 





21-2 



i6-5 



15-5 



ig-Q 





i6-5 



IQ-Q 



2-8 



Max. diam. of mouth 





12-5 



10-5 



9-6 



10-8 





90 



4-5 



1-2 



Spire (dorsal view) 





12-5 



127 



II-2 



11-6 





12-5 







Max. diam. to height 





I : 1-27 



I : 1-33 



i: 1-3 



r : I- 



35 



I : !■ 



43 r : 



I '39 I : 1-43 



Diam. to height of mouth 



i: 17 



I : 1-57 



I : i-6i 



I : I 



76 



i: I 



•831; 



2-22 i: 2-33 



Diam. mouth to max. 



diam. 



I : 2-67 



I : 2-59 



i: 2-8i 



I : 2 



78 



I; 3 



•02 I : 



3 I : 2-92 



Spire to total height 





i: 3-4 



I : 3-01 



i: 3-12 



I : 3-44 



i: 3 



'2 





In the type- specimen, therefore, the height of the shell is about 1 1 times the 

 maximum diameter, which is about 2-^^ that of the mouth ; the height of the spire is 



