I92I.] 



B. Prashad : Notes on LamdUhranchs. 



115 



to dark 1:)rown or even black, nacre whitish, light yellow near the 

 margin and having a violet border. 



Geographical Distribution. — -The species, so far as is known, 

 is endemic in Peninsular India on the Malabar Coast only. It 

 occurs in brackish water areas though specimens are sometimes 

 carried into nearly fresh water. 



Soft parts.— The animal is somewhat trigonal, but the greater 

 part of the umbonal region is occupied by a triangular structure 

 formed by the union of the mantle flaps of the two sides only, 

 the rest of the soft parts being somewhat elliptic in outline and 

 lying below this hollow structure. Specimens preserved in spirit 

 are of a whitish colour with dark brown black border in the region 

 of the mantle papillae on the inner surface only, but seen through 

 the translucent mantle flaps, the adductor muscles are dark 

 yellow. 



The mantle is very thin and translucent up to the palleal 

 junction, below which, owing to the large numbers of radiating 

 muscle fibres, it becomes much 



thicker ; in the region of the '"^ 



papillae it is very thick and 

 opaque. The border is entire 

 without any papillae on the 

 edge, but a continuous row of 

 small finger-like papillae of a 

 dark brownish colour with 

 whitish tips is present on the 

 internal surface a little distance 

 from the margin. The papillae 

 are of the same size throughout, 

 and are not reduced in the 

 middle region of the bucco- 

 pedal orifice as in the genus 

 Corhiciila} The papillae are 

 also present on the line of union 

 of the mantle flaps in the 

 siphonal region above and below the two siphonal orifices. The 

 two mantle flaps are united with each other anteriorly to a little 

 above the anterior adductor muscle, the two then separate but in 

 the region of the muscle itself the free portion is not very broad 

 owing to the muscle lying near the border ; behind the muscle, how- 

 ever, the two flaps are quite separate forming the large bucco- 

 pedal orifice, which extends posteriorly in line with the posterior 

 margin of the posterior adductor muscle. From the point of ter- 

 mination of the bucco-pedal orifice the siphonal orifice starts. The 

 flaps of the mantle are united in this region in the situation of the 

 mantle papillae except for the openings of the two siphons ; the 

 line of union is indicated by the row of papillae in this region. 



Text-fjg. I. — Soil parts of V. cypri- 

 II aides (Gray). 

 F. =foot ; I. G.=- inner gill ; M. — 

 mantle ; M. P . = mantle papillae ; 

 O. G. = outer gill ; P. palp ; S. = 

 siphons. 



' Prashad. Rec.Ind. Mus. Will. pp. 209—211 (1920). 



