6io 



Records of the Indian Museum. [Vol. XXII, 



Arcidopsis footei (Theobald). The genus therefore appears to be 

 a true Eastern one confined to Assam, Burma, Siam, Cambodia 

 and Sumatra. 



In the collection the genus is represented by a single shell 

 of T. misellus (^lorelet) from the Manipur Vallej^ and by many 

 specimens of a new species from the base of the Naga Hills, 

 Assam. Living specimens of the new species were brought to 

 Calcutta by Mr. S. L. Horn and from these I am able to describe 

 the hitheito unknown animal of this genus. 



Animal with the outer and inner gills of nearly the same width 

 posteriorly, but the outer shorter in length than the inner; inner 

 lamellae of the inner pair of gills united in the anterior f of their 

 length to the abdominal mass oir each side while in the posterior 

 third the lamellae of the two sides are united with each other to 

 the end. Palpi large. Mantle entire with quite simple margin. 

 Branchial aperture large, of a light brownish colour, with many 



O.G. 



Sa,. 



C'An.. 



■:Br. 



I.G. 



Pig. 3u. — Soft parts ot Trapesotdeus dhanusliori, Prasliad. 



An. Anal aperture ; By. branchial aperture : F. foot : I.G. inner srill ; P. palp ; 

 0. G. outer grill ; 5'(7. supra-anal aperture. 



rows of elongate papillae along the border. Anal aperture about 

 I the size of the branchial, dark brown in colour and with a 

 single row of minute papillae on its margins, supra-anal distinct, 

 smaller than the anal and separated from it by a mantle connec- 

 tion about half the size of the anal. Marsupium formed by all 

 the four gills. 



Trapezoideus misellus (Morelet). 



19UO. Trapezoideus misellus, Simpson, op. cit., p. 859. 



1914. Ti'apez'iideus misellus, Simpson, op. cit., pp. 1182. 1183. 



1915. Trapezoideus misellus, Preston, op. cit., p. 194. 



Mr. S. L. Hora picked up a dead shell of a half-grown speci- 

 men of this species at the edge of a swamp about five miles from 

 the Thoubal Stream in the Manipur Valley. 



The shell is quite typical in shape and hinge, but does not 

 show any sculpture owing to the umbones being eroded. 



The species was previously known from Siam, Tenasserim and 

 Burma onlv. 



