CYCLOTACEA. 263 



19. Pterocycliis (Rhiostoma) housei, Haines. 



2 Siam ; ex c. Mr. Cuming. 



20. Pterocyclus (Rhiostoma) hainesi, Pfeiffer. 



1 Siam J coll. Baron F. von Ricbtliofen. 



Sub-Genus OPISTHOPORUS, Benson. 



21. Pterocyclus (Opisthopoms) birostris, Pfeiifer. 



1 Borneo ; ex e. Mr. Cuming. 



22. Pterocyclus (Opisthoporus) euryomphalus, Pfr. 



1 Borneo ; ex c. G. Nevill, Esq. 



23. Pterocyclus (Opisthoporus) biciliatus, Mss. 



2 Borneo ; ex c. Mr. Cuming. 



24. Pterocyclus (Opisthoporus) solutus, Stoliczka. 



8 Penang (type); coll. Dr. F. Stoliczka. 



8 Buket Pondong ; coll. Dr. Edmund Townsend. 



25. Pterocyclus (Opisthoporus) penangensis, Stol. 



14 Penang (type) ; coll. Dr. F. Stoliczka. 



14 Buket Pondong ; coll. Dr. Edmund Townsend. 



Sub-Genus SPIRACULUM, Pearson (type P. hispidus, 



Pearson). 



26. Pterocyclus (Spiraculum) hispidus, Pearson. 



3 North-East Frontier, Bengal (type) ; ex As. Soc, Bengal. 

 16 Teria Ghat; coll. Major H. H. Godwin- Austen. 



var. minor (? distinct species). 



2 North-East Frontier; ex As. Soc, Bengal. 



9 Teria Ghat; coll. Major H. H. Godwin- Austen; two of these Dr. F. 

 Stoliczka labelled $ and one $ (slightly larger). 



27. Pterocyclus (Spiraculum) mastersi, Hani. & 



Theob. 

 15 Upper Assam (typical) ; coll. Mr. Masters. 



var. simplex (? distinct species). 



Of much simpler characters tlian the typical form. The last 

 whorl only a little detached ; the sutural tube not bent back ; 



