582 



Records of the Indian Museum. 



[Vol. XXII, 



base of the tentacles. The edge of the mantle is somewhat thick- 

 ened and the left epipodial lobe is well developed to form an ear- 

 shaped incomplete funnel or pulmonary siphon. Lying e.xternally 

 and posterior to the siphon a secondary pallial branchial process 

 projects outwards and backwards. When fully expanded this process 

 is elongate, band-shaped and bluntly pointed. In longitudinal sec- 

 Lion it would be coarsely 

 and strongly sinuate owing 

 to alternate convexities and 

 concavities on its surface. 

 When contracted it has the 

 appearance of a strongly 

 pleated or folded foliate 

 body ; in some cases the 

 pleats are large and appear 

 like lamellae. 



In the radula tneie are 

 about 75 longitudinal rows of 

 teeth with the approximate 

 dental formula 26. 12. 1. 12.26. 

 The external marginals are, 

 however, ver}' ill-developed 

 and the transition between 

 the outer laterals and inner 

 marginals is so gradual that 

 it is difficult to fix the point of separation. The free lobe of the 

 central is large and bilobed. Its base is relatively long and narrow. 

 The marginals have their cusps long, stout and sharp. In other 

 respects the teeth do not offer any peculiarities bej'ond those 

 noticed in the generic description. 



Fig. 15. — Longitudinal section of the sec 

 ondary branchial process of Indoplanorbii 

 exustiis (Desha3'es). 



Gyraulus, Agassiz. 



1837. Gj'7'anliis, .\gassiz, De Cliarpeutier Cat. Moll . tcrr.fluv. Suisse : 



Neti. Deu. Scliw. Ges. Nat. I, p. 21, 

 1919. Gvrauliis. Annandale and Prashad. Rec.liid. Afiis. Will, p. 5.?. 



We have nothing to add to our recent account of the genus, 

 except that Benson's species Planorbis cantori is not a Segnientina, 

 as Preston thought, but belongs to this genus. 



Gyraulus convexiusculus (Hutton). 



1919. Gyraulus coiivexiuscdus, Annandale and Prashad, Rec. hui. 

 Mus. XVIII, pp. 52-54, figs sK, 7a, 8i. 



In the Manipur Valley the species is not so common as it is in 

 other parts of India; and seems to be replaced to a large extent 

 by G. cantori. 



The only specimens collected in the valley are from a shallow- 

 pond in front of the Residency at Imphal and an artificial tank 

 at Mingyang Pukri in the same town. 



