130 On some Land- Shells from Vanbu, Tonkin. 



discovered, stands as a well-marked recognizable species. 

 That such links will eventually be found is very probable, in 

 which case the specific name here suggested may be used in 

 a varietal sense. 



Instances in which keeled varieties of species with a 

 normally rounded body-whorl occur might be mentioned ; 

 but I doubt if such an extreme case as the present could be 

 shown. 



Eulota rostrella, var. 



Helix rostrella, Pfeiffer, Novitates Conch, vol. iii. p. 379, pi. lxxxviii. 

 figs. 1-3 ; Pilsbry, Man. Con. ser. 2, vol. vii. p. 83, pi. xviii. figs. 48- 

 60 (after Pfr.). 



Bah. Lao Mountains, Cambodia. 



Two specimens from Vanbu, Tonkin, differ from the 

 typical form in being a trifle more widely umbilicated and 

 rather less acutely carinate, the form of the peristome being 

 consequently more regularly curved at the termination of the 

 keel. 



Pterocyclus vanbuensis. 



Testa parva, discoidea, latissime umbilicata, lutea, maculis castaneis 

 supra radiatim arcuatis picta, infra peripheriam zona angusta 

 castanea cincta, limo undique induta ; anfractus 5, convexi, incre- 

 menti lineis tenuibus striati, striis spiralibus tenuissimis obsolete 

 sculpti ; apertura circularis ; peristoma duplex, margine externo 

 leviter expanso, ad suturam haud profunde sinuato ; operculum 

 corneum, utrinque in medio concavum, multispirale, supra con- 

 centrice lamellatum, lamellis ad marginem aculeatis. 



Diam. maj. 10 millim., min. 8|, alt. 5 ; apertura 3^ lata. 



This species has the habit of coating its surface with mud, 

 thus concealing the colour-markings. In form and colora- 

 tion it recalls Pt. rupestris, Benson, the type of the genus. 

 It is, however, smaller, the lateral notch is shallower, and the 

 alseform expansion above it is only feebly indicated. The 

 operculum also is more horny and flatter. The species might 

 also be compared with the large Pt. planorbulus (Lamk.) as 

 regards the general form, the character of the notch in the 

 peristome, and the operculum. 



