PTEROCYCLOS.— Plate V. 



Species 27. (Pig. a, b, Mus. Cuming.) 



Pterocyclos anomalus. Pter. testa, latissime aperte 

 umbiUcatd, discoideii, fulvescente-albd, rufo-fusco un- 

 dique nifide undaio-strigatd, atifractibus rotundatia, 

 decussalhn st?'iai/.s, anfraclu ultimo tubulo suturali 

 recmnbente pone aperturam ; aperturd oblique circu- 

 lari, labro late plano-reflexo, superne subdilatato, simi 

 fere obsoleto. 



The anomalous Pterocyclos. Shell very broadly 

 openly uinbilicated, discoid, fidvous-white, neatly 

 wave-streaked throughout with red-brown, whorls 

 rounded, decussately striated, last v/horl with a re- 

 cumbent sutm-al tube behind the aperture ; aperture 

 obliquely circular, lip broadly flatly reflected, a little 

 dilated at the upper part, sinus almost obsolete. 



Cyclostoma pterocycloides, Pfeiffer, Pro. Zool. Soc. 1854, 

 p. 300. 



Cyclotus pterocycloides, Pfeiffer. 

 Opislhoporm pterocycloides, Pfciff'er. 



Hub. Borneo. 



The tube of this species is recumbent in the suture. 



Species 28. (Mus. Cuming.) 



Pterocyclos tener. Tter. testa ampliter umbiUcatd, 

 subdiscoided, pelliicido-luted, anfractibus rotimdatis, 

 nndique tenue. a?inuluto-striatis ; aperturd circidari, 

 labro tenia, dupUcato, sinu in tubulo mimdo recurvo 

 producto. 



The delicate Pterocyclos. Shell largely umbili- 

 cated, subdiscoid, transparent yellow, whorls rounded, 

 finely ring-striated throughout ; aperture circidar, lip 

 thm, duplicate, sin\is produced into a small recurved 

 tube. 



Menke, Malak. Blat. 1856, p. 69. 

 Rhiostoma tener, Benson. 



Hab. Cochin-China. 



A delicate semitransparent shining yeUow shell, ringed 

 throughout with thread-like strife. 



Species 29. (Mus. Cuming.) 



Pterocyclos euryomphalus. Pter. testa latissime per- 

 aperte umbiUcatd, plano-discoided, fulvd, castaneo 

 nndique acute undatd, spird subimmersd, anfractibus 

 angustis, rotundatis, tenuistriatis, anfractu ultimo tu- 

 bulo parvo recurvo subremote pone aperturam ; aper- 

 turd oblique circulari, labro dupUcato, superne tenue 

 tmnido-dilatato. 



The widely-umbilicated Pterocyclos. Shell very 

 widely very openly umbilicated, flatly discoid, fulvous, 

 sharply waved throughout with chestnut, spire rather 

 immersed, whorls narrow, roimded, flnely striated, 

 last whorl with a small recurved tube at some dis- 

 tance behind the aperture ; aperture obliquely circu- 

 lar, lip duplicate, thinly tumidly dilated at the upper 

 part. 



Cyclostoma euryomphalus, Pfeiffer, Pro. Zool. Soc. 1856, 

 p. 337. 

 Opisthoporus euryomphalus, Pfeiffer. 



Hab. Borneo. 



Very slenderly discoidly coiled, with a crowded painting 

 of sharply zigzag chestnut streaks. 



Species 30. (Mus. Benson.) 



Pterocyclos Haughtoni. Pter. testa ampliter umbi- 

 Ucatd, subdiscoided, fulvo-albidd, superne rufo-fusco 

 tinctd, ad peripheriam fasciatd et nndulatd, anfracti- 

 bus declivi-rotundatis, dense plicato-striatis, anfractu 

 ultimo soluto ; aperturd circulari, labro vix reflexo, 

 sinu erecto-auriculato, subrecurvo. 



Haughton's Pterocyclos. Shell largely umbilicated, 

 subdiscoid, fulvous-white, stained on the upper part 

 with red-brown, banded and delicately waved at the 

 periphery, whorls slopingly rounded, closely plicately 

 striated, last uncoiled ; aperture circidar, lip scarcely 

 reflected, sinus erectly auriculated, a little recurved. 



Rhiostoma Haiiyhtoni, Benson, Ann. Nat. Hist. ser. 3. 

 vol. 5. p. 96. 



Hab. Moulmein, India. 



A very distinct dark-stained species, in which the sinus 

 assumes the form of a recurved section of a tube. 



