60 Records of the Indian Museum, [VoL. XViar 
Measurements of Shells (in millimetres). 
Specimens A—C belong to phase A: specimens D—F to phase B. 
A B C D E F 
Length 07:84. 968 2790321271 1407 30. 15 ato 
Height 55.5) 40°9-47 6.304 3078 20g 
Thickness BTA Boies 3BNe t25 25°3.. 160% 
Lamellidens marginalis subsp. rhadinaeus is common all over 
SP eS ad SURG 
SSE RET SEN. 
"oe ve, < <5 Pp fOr . 
LO OE SS 
yore f 
Ste, 
et 
FG. 9.—Shells Lamellidens marginalis rhadinaeus, subsp. nov. (natural size). 
A. Dorsal view of type-specimen from a backwater of an effluent of the 
Helmand near Nasratabad, Seistan. 
B. Hinges and scars of the same specimen. 
Seistan and broken shells from the Afghan desert evidently belong 
to the same form. It appears to be quite distinct from the var. 
candaharica, with specimens of which we have compared our series. 
The range of the species, which is a very plastic one, is more 
