1G6 RecorJ'i of the Indian 3Iuseu>ii. [Vol. XV, 



Westerlund calls L. jieregriformis merely " L. jjeregra var. " L. peregri- 

 fonnis, whatever its precise status may be, lias hitherto been recorded 

 only from the Lake of Horns in Asia Minor. 



Limnaea subpersica, Locard. 

 (Plate XX, fig. 5.) 



1883. Limnaea suhjKrsica, Locard, oj^. cit., p. 285, pi. xxiii, figs. 38-40. 



Some still smaller shells (greatest length 9 mm.) from the same 

 deposit agree fairly well with Locard's figure, but show considerable 

 variation in the form of the aperture. Westerlund (fide Kobelt, op. cit., 

 p. 7) regards the form as a variety of L. lagotis. It was found with L. 

 peregriformis in the Lake of Homs. 



Family PLANOEBIDAE. 



1906. PlaiKubidac, Pelseneer, "MoUusca" iu Laiikestcr's Trealise. on Zooloyy, 

 Vol. V, p. 185. 



Genus Planorbis, Guttard. 



The only species of this genus represented in the collection belongs 

 to the section or subgenus Gyraulus, Agassiz. 



Planorbis convexiusculus, Hatton. 



187(5. Planorbis convexiusciduti, Hauley and Theobald, ConcJt. Iiid., pi. xcix, figs. 



8, 9, 10. 

 1918. Planorbis saigoncmis {".), Aunandale, Rec. Incl. Mus. XIV, p. 112, pi. xi, 



fig. 1. 



I have been in some doubt whether this form was more than a variety 

 of P. saigonensis, Crosse & Fischer (=P. campressus, Hutton), but, 

 having recently had an opportunity of examining good series of fresh 

 specimens of both, I am now convinced that they are specifically distinct. 

 P. saigonensis is a more constant species than P. convexiusculus, which 

 exhibits considerable individual variability in the form of the shell. 

 In most individuals of the latter species there is no peripheral keel or 

 angulation, but it is not uncommon for a distinct angulation to be 

 present. P. saigonensis has a larger, flatter, coarser and more irregularly 

 sculptured shell, which is distinctly carinate. There is also a difference 

 in the shape of the aperture. I have recently seen a number of speci- 

 mens of P. sm^rowcHSis from Lahore which have traces of the bacterial 

 velum so noticeable in P. velifer^ ; some also possess spiral rows of 

 epidermal cilia as in the var. ciliata of that species, from which both 

 P. convexiusculus and P. saigonensis differ considerably in the shape 

 of the mouth of the shell. 



Shells of P. convexiusculus very like those from deposits in the Shan 

 States are abundant in the samples from all the deposits at Nasariyeh 

 and Samara. The species was described from Afghanistan and is common 

 in northern India. 



1 Annandalc, Rcc. Ind. Mus. XIV, p. 112, pi. xi, figs. 7-11 (1918). 



