472 Records of the Indian Museum. [\'ol. XXII, 



exusfus, Deshayes. as the type of a distinct genus oil purely ana- 

 tomical grounds. A full account of the animal and our reasons 

 for adopting this course are given in a paper shortly to be pub- 

 lished in the Records of the Indian Museum, but a few notes are 

 included here to facilitate reference. 



Indoplanorbis cxustus (Deshaj'es). 



1S34. Planorbis exiistiis, Deshayes, Voyage Belangcr /ndes-Onent. 



Zool .. p. 417, pi. i, figs. 11-13. 

 1836. Planorbis indiais, Benson, Joitrn. As. Soc. Bengal \', p. 743. 

 1856. Planorbis Coromaiideliciis and P. zebriniis, Dunker, in Mart. 



Chemn. Conch.-Cab, pp. 43, 57, pi. vi, figs. 14-16, 20, 22, and 



pi. vi, figs. 11-13. 

 1876. Planorbis exusfus, ? P. sebrintis .ind P. Merguieiisis, Hanlev 



and Theobald, Conch. Itui.. pp. XX'Ill and 18, 60, pi. xi, 



tig. I. pi. cli. figs. 5, 0. 

 1878. Planoi'bis exiistus P. Coromandeliciis, P. eburneus, P. brunneus, 



P. Mei'giiiensis and P. orientatis, Sowerb)' in Reeve's Condi. 



Icon., pi. iv, figs. 31, 34 . pi. \, figs. 38 a — c, 400, b ; pi. xi, fig. 



85 and fig. 89. 

 1897. Planorbis exusfus (Coromandeliciis, Beck, Indicts, Benson), v. 



Martens, op. cit., p. 12. 

 1915. Planorbis exusfus with vars. ebnrneus. brunneus and zonatiis. 



P. zebtinus, P. orientalis and P. Merguiensis, Preston, Faun, 



Brit. Ind. Freslnv.-.Moll.pp. 115-118. 



Dr. L. Germain of the Paris Museum, after a detailed exami- 

 nation of numerous shells of this species in the large collection of 

 Planorbidae ' in the Indian Museum has concluded that the various 

 so-called species (with the exception of P. orientalis, Ivomarck)^ 

 included in the synonymj' given above are all synonymous and 

 should be known as P. exustus, Deshayes. I include P. orientalis^ 

 Lamarck, also in this s^^nonj'my as the differences noted by 

 Lamarck* are of the same nature as the variations exhibited so 

 commonly by this very variable species. The reasons that 

 prompted Dr. Annandale and myself to create the new genus 

 Indoplanorbis ma}' be briefly stated as follows :■ — The branchial 

 process is not a simple structure as in other members of the genus 

 Planorbis, Geoff., but is distinctly lobed, the radula is rather large 

 and broad and the penis is a long cj-lindrical tube without any 

 stylet or retractor muscles. 



Von Martens (loc. cit.) recorded the occurrence of this species 

 from near Deli, Sumatra and in the present collection there are 

 latge numbers of specimens from various localities. Dr. L. 

 Germain in his " Catalogue," referred to already, has discussed at 

 length the variations exhibited by this species in the form of the 

 spire, the mouth-aperture, the size of the shell, its colour and 

 structure, and the sculpture on the various whorls. All these 



'^ The results of Dr. Germain's work on the Indian Museum collection are 

 being published as a special volume in the Records of fhe Indian ,)/useum. and 

 1 have had the advantage of consulting the original manuscript and drawings of 

 this valuable work. 



2 His. Nat..Anim. Veytcbres. 2nd edition, p. 385 (183S). 



