THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[THIRD SERIES.] 

 No. 113. MAY 1867. 



XLIV. — On the Genus Plectostoma, H.Adams, and on the Animal 

 of Diplommatina, Benson. By William T. Blanford, 

 A.R.S.M., F.G.S. 



1. On the Genus Plectostoma. 



In the 'Natural History Review' for 1864, p. 599, there ap- 

 peared a letter from Mr. DeCrespigny, of Labuan, briefly de- 

 scribing a minute land-shell which he considered a living repre- 

 sentative of the Triassic genus Scoliostoma. In an editorial note 

 it was stated that the specimens accompanying the letter had 

 been submitted to Mr. H. Woodward, of the British Museum, 

 and were considered by that naturalist to be " closely allied to, 

 if not identical with, Opisthostoma/* described and figured by 

 my brother in our joint paper published in the * Journal of the 

 Asiatic Society of Bengal' for 1860. 



In the March Number of the ^Annals' for 1865, p. 177, a 

 shell, evidently the same as that referred to in the ' Nat. Hist. 

 Review,' was described by Mr. H. Adams as the type of a new 

 genus belonging to the Helicidse, and named Plectostoma De- 

 Crespignii. In neither of the two notices is any mention made 

 of the animal. I recently called attention, when describing a 

 second species of Opisthostoma from Western Africa, in the 

 ' Proc. Zool. Soc.,' to the great similarity of external form be- 

 tween Plectostoma BeCrespignii and the Burmese Helicidous 

 genus Hypselostoma. I had then only seen a photograph copy 

 of a drawing of the Plectostoma^ for which I was indebted to 

 Mr. Benson. W^ithin the last few days I have received speci- 

 mens of this most interesting form from Mr. Damon ; and from 

 an examination of them I am convinced that Mr. H. Woodward's 

 opinion of the affinities of the species is correct, and that it dif- 

 fers in no essential characters from Opisthostoma. In the paper 

 just referred to as sent to the Zoological Society of London, I 

 have shown, from an examination of the animal and operculum, 



Ann, ^ Mag. N. Hist. Ser. 3. Vol. xix. 23 



