Mr. W. H. Benson on two species 0/ Pterocyclos. 195 



"from Sumatra" on the authority of Lafargue. A gigantic 

 Cyclostoma appears as C. oculus Capri, from the same island, on 

 the like authority, in the collection. Having pointed out these 

 shells to Dr. PfeifFer's notice, further information respecting 

 them may eventually be obtained in the Supplement to his 

 ' Monograph.^ 

 Dublin, ard July, 1851. 



P.S. — Two other species have been assigned to India, C. Turbo, 

 Ch., and C. tincarinatum, Miill. ; the former by Chemnitz, who cites 

 Tranquebar and Coromandel as the habitat. Later observers 

 have not confirmed this reference, Sowerby mentions Sumatra, 

 but quotes no authority. C. tricarinatum is attributed by the 

 last-named author to India. The form at once suggests an East 

 African insular origin, and Petit de la Saussaye refers it to the 

 Mauritius, citing however no authority in the ' Journal de Con- 

 chyliologie.' I am able to corroborate this statement. Sir David 

 Barclay presented me with a worn and bleached specimen which 

 he had himself picked up in the island at the Caverns of M. du 

 Plessis, near the Petite Riviere; and he showed me another 

 specimen, recently dead, which had just been brought to him from 

 the woods. 



Cyclostoma Michaudi, Grat. [carinatum, Sowerby), for which 

 no locality is given in the ' Thesaurus,' and which Petit ascribes 

 to Madagascai", was procured by Sir D. Barclay from the Piton 

 de la Riviere Noire in the Mauritius. They occurred with both 

 a white and an orange peristome. In the former variety the 

 carinae were more distant, as shown in Sowerby's figures ; it may 

 perhaps be found to constitute a distinct species. 



Dublin, July 5, 1851. 



XVII. — Descriptive characters of two species of the Genus Ptero- 

 cyclos, discovered by Dr. Bland. By W. H. Benson, Esq. 



[With a Plate.] 



In the 5th volume of the Journal of the Asiatic Society of Cal- 

 cutta, Dr. William Bland, of H.M.S. Wolf, published, in 1836, a 

 note on two unnamed species of Ptei'ocyclos, to which, on inspec- 

 tion of the coloured drawings forwarded to me by the Secretary, 

 but unfortunately not engraved, I added a note on their affinities. 

 Previously to returning them to Mr. James Prinsep, I took a 

 pencil outline of the figures, for the pui-pose of reference, and 

 from these outlines, with the assistance of Dr. Bland's note, I 

 now endeavour, at Dr. PfeifFer's suggestion, to affix specific cha- 

 racters (necessarily imperfect) to two novel forms of a rare and 



13* 



