26 OPISTHOPORUS. 



Testa depressa, orbicularis, late umbilicata, sutura pone 

 aperturam tubulo exserto, pervio munita. Peristoma duplex. 

 Opisthoporus Benson in litt. (Conf. Zeitschr. f. Malak. 1851. p. 8.) 



— Albcrs in Zeitschr. f. Malak. 1852. p. 120. (ex parte.) 



— Benson in Ann. and Mag. 1855. 2d. ser. XV. p. 13. 



— H. et A. Adams Gen. rec. Moll. II. p. 276: genus Cy- 



clotinarum. 

 PlerocycU sp. Mouss. 

 Cycloti sp. Pfr., Gray. 



CI. Benson (I. c. p. 15) iiomen generis cum Coelopo- 

 mate niutnri proponit, si species observarentur eadem operculi 

 structura praeditae, sed tubulo suturali carentes. 



Species hodie cognitae sunt sequentcs : 



1. biclliatlis JTIouss. (Coll. 34. — Bens. in Ann. 

 and Mag. 2d. ser. XV. p. 14. — y^c/. Gen. II. p. 276. 

 t. 85. f. 2. — Plerocyclos bicilialus Mouss., Pfr. 

 Mon. Pneum. p. 50. n. 16. — Gray Phan. p. 32. — 

 Chcmn. ed. nov. p. 234. t. 43. f. 1 — 3. — Cyclo- 

 stoma Taylorianwn Pfr., Chemn. ed. nov. p. 288. 

 t. 38. f. 27 — 29. — Cyclost. Charbonnieri Recl. 

 in Journ. Conch. 1851. II. p. 214. t. 5. f. 12. 13. — 

 Cyclotus Taylorianus Pfr. Mon. Pneum. n. 44. — 

 Gray Phan. p. 24.) Mon. p. 40. 



2. O. euryoniplialtis Pfr. 



T. late umbilicata, depressa, subdiscoidea, solidula, stria- 

 tula, lutescens, striffis angulosis castaneis superne latis, subtus 

 linearibus picta; spira plana, vertice nigro vix prominulo; 

 anfr. ^i/^, prope suturam canaliculatam subangulati, ultimus 

 antice vix descendens, 4 mill. pone aperturam spiraculo brevi 

 retroflexo munitus; umbilicus dimidium diametri fere occupans; 

 apertura diagonalis, subcircularis ; perist. duplex: internum 

 breviter expansum, ad anfractum penultimum subincisum, ex- 

 ternum superne alatim dilatatum, latere dextro patens, sinistro 

 obsoletum. — Operc. normale. — Diam. maj. 15, min. 12, 

 alt. 4 mill. Ap. diam. 4 mill. (Mus. Cuming.) 



Cyclostoma euryomphalum (0^{&i\io^ori\s) Pfr. in Proc. Zool. Soc. 1856. 

 p. 337. 



Habitat in insula Borneo. 



Obs. Differt ab 0. biciliato praesertim umbilico multo latiore. 



* 



3. rogtellatllS Pfr. {Bens. in Ann. and Mag. 2d. 

 ser. XV. p. 14. — Ad. Gen. p. 277. — Cyclost. 

 rostcllatum Pfr. in Chemn. ed. nov. p. 289. t. 38. 

 •f. 30 — 34. — Cyc/otus rostfllatus Pfr. Pneum. 

 n. 45, — Gray Phan. p. 24.) Mon. p. 40. 



