I92I.] 



B. Prashad : The ecnus Tricula. 



69 



flowing through a marsh at the head of the Bhim Tal Lake in the 

 United Provinces. Besides these there are a few specimens in the 

 Indian Museum collection from Naini Tal. 



Tricula gravelyi, sp. nov. 



The shell of this species is elongate-ovate, not more than if as 

 long as broad, with an obtuse apex consisting of 5i-6|- whorls and 

 of a pale yellowish colour. The whorls increase regularlj- and are 

 evenly swollen. The suture is oblique, deeply impressed but not 

 canaliculate. The first two whorls are minute, but the others in- 

 crease regularly and evenly in size ; the body-whorl is fairly tumid, 

 narrow, about twice as broad as the penultimate whorl and band- 

 shaped in dorsal view. The lobe corresponding to the anterior 

 angle of the mouth seen in dorsal view and described for T. montana 

 is present, but is not so deep, both the inner and outer margins 

 are sharply curved. The mouth is oblique, rather smaller than in 

 T. montana, ovate and narrowlj^ rounded above. The peristome - 

 is continuous and the columellar lip is of the same thickness 

 throughout, the outer margin is onlj- narrowly recurved back- 

 wards. The shell is sub-umbilicate or even umbilicate. 



I give below the measurements of three specimens of each 

 species for comparison. 



Measurements {in millimetres). 



Length of shell 

 Breadth of shell 

 Length of aperture 

 Breadth of aperture 



3'5 

 17 

 1-6 



i"i5 



Type series. — No. M 11 89 5/2 in the registers of the Zoological 

 Survey of India (Indian Museum). 



Habitat. S^&c\m.&ns of this interesting form were collecterl 

 by Dr. F. H. Gravely in still creeks amongst small islands in the 

 bed of the Nerbudda River at Hoshangabad in the Central Provin- 

 ces of India in March 19 19, attached to weeds. 



