196 Mr. W. H. Benson on two species of Pterocyclos. 



interesting genus, of which eleven distinct Asiatic species may 

 now be enumerated, viz. : — 



1. Pterocyclos rupestris, Benson, 1832, Bahar. 



2. hispidus, Pearson, 1833, Khasya Hills. 



3. parvus, Pearson, 1833, Khasya Hills. 



4. anguliferus, Soul. 1841, Cochin China. 



5. bilabiatus, Sow. 1843, South India. 



6. Albersi, Pfeiffer, 1847. 



7. biciliatus, Mousson, 1849, Burma. 



8. spiracellum, Ad. & Reeve, 1850, Borneo. 



9. Cumingi, Pfr. 1851, Ceylon. 



10. Blandly nobis, Straits of Malacca. 



11. Troscheli, nobis, Ceylon. 



Full descriptions of the species, and the specimens themselves, 

 having been so long withheld from the public eye, I have over- 

 come my objection to publish characters, founded on the only 

 materials available, in the hope that more particular attention 

 may be directed to these shells by travellers who may have oppor- 

 tunities for exploring the localities whence they were obtained. 



Pterocyclos Blandi, nobis. 



Testa latissime umbilicata, orbiculato-depressa, albida, strigis undatis 

 radiatis fusco-aurantiis, fasciaque unica saturatiore ad periphseriam 

 ornata ; anfractibus A\ rapide accrescentibus, ultimo antice subito 

 valde alatim dilatato ; apertura obliqua, peristomate subduplici, 

 interno incrassato, superne libero sinuato, externo superne valde 

 expanso, ala soluta antice angulata, descendente, supra anfractum 

 penultimum projecta, postice sinum exhibente munito ; umbilico 

 latissimo. 



Diam. 1 inch. Bland. 



Diam. major 29, minor 23 mill, ex icone. 



Hah. ad Pulo Susson insulam prope Pulo Penang jacentem. Teste 

 Bland. 



Pterocyclos Troscheli, nobis. 



Testa latissime umbilicata, orbiculato-depressa ; anfractibus 4 lente 

 accrescentibus, ultimo antice subdilatato ; apertura circulari peri- 

 stomate incrassato, reflexo, superne antice obsolete sinuato, ala cu- 

 cullata, antice angulata, deflexa, anfractui penultimo adhaerente ; 

 umbilico latissimo. 



Operculo convexo, corneo. 



Diam. t 7 q inch. Bland. 



Diam. major 20, minor 18 mill, ex icone. 



Hab. ad Trincomalee Insulse Ceylon. Teste Bland. 



In character it approaches the group Myxostoma of Troschel, 

 to whom I have the pleasure of dedicating this species of a genus, 



